Force labels of \subfloat to the centre of \textwidth

Question

I made two timelines using https://tex.stackexchange.com/a/442718/164280. This gives me the following timelines (I added \showframe to show how far off it is):

This is the code used for calling the figures:

\PassOptionsToPackage{table,dvipsnames,svgnames}{xcolor}
\documentclass[11pt, twoside, a4paper]{report}
\usepackage[inner = 30mm, outer = 20mm,  top = 30mm, bottom = 20mm,     headheight = 13.6pt]{geometry}
\usepackage{emptypage}
\usepackage[toc,page]{appendix}
\usepackage{tikz}
\usetikzlibrary{calc,fit,arrows.meta,calc,positioning}
\usepackage{xifthen}
\usepackage[pdfpagelayout=TwoPageRight]{hyperref}
\usepackage{listings}
\usepackage{multicol}
\usepackage{apacite}
\usepackage{color}
\usepackage{textcomp}
\usepackage{chngcntr}
\usepackage[export]{adjustbox}
\hypersetup{colorlinks=true, linktoc=all, allcolors=green!30!black,}
\usepackage{booktabs, siunitx, caption}
\newcommand{\source}[1]{\vspace{-8pt} \caption*{ Source: {#1}} }
\usepackage{amsmath}
\usepackage{graphicx}
\usepackage{slashbox}
\usepackage[caption=false]{subfig}
\usepackage{array}
\newlength\tbspace
\setlength\tbspace{3cm}
\newcolumntype{L}{l<{\hspace{\tbspace}}}

\usepackage{wrapfig}
\graphicspath{ {./Figures/} }
\usepackage{gensymb}
\usepackage{etoolbox}% http://ctan.org/pkg/etoolbox
\makeatletter
\patchcmd{\@makechapterhead}{\vspace*{50\p@}}{}{}{}% Removes space above                \chapter head
\patchcmd{\@makeschapterhead}{\vspace*{50\p@}}{}{}{}% Removes space above       \chapter* head
\makeatother
\usepackage{pgfplots}
\pgfplotsset{compat=1.11,
    /pgfplots/ybar legend/.style={
        /pgfplots/legend image code/.code={%
            \draw[##1,/tikz/.cd,yshift=-0.25em]
            (0cm,0cm) rectangle (3pt,0.8em);},},}
\usepgfplotslibrary{statistics}
\usetikzlibrary{arrows}
\usepackage{tcolorbox}
\usepackage{fancyhdr}
\usepackage{layouts}
\usepackage{chronology}
\usepackage{showframe}
\raggedbottom
\fancyfoot{}
\fancyhead{}
\fancyfoot[LE]{\thepage}
\fancyfoot[RO]{\thepage}
\fancyhead[LE]{\nouppercase{\leftmark}}
\fancyhead[RO]{\nouppercase{\rightmark}}
\pagestyle{fancy}

%% Redefine the plain page style so chapter pages match my footer preference
\fancypagestyle{plain}{%
\fancyhf{}%
\fancyfoot[LE]{\thepage}
\fancyfoot[RO]{\thepage}
\renewcommand{\headrulewidth}{0pt}% Line at the header invisible
\renewcommand{\footrulewidth}{0pt}% Line at the footer visible
}


\colorlet{A}{gray}
\colorlet{B}{lightgray}
\colorlet{C}{white}

\pgfdeclarelayer{background}
\pgfdeclarelayer{foreground}
\pgfsetlayers{background,main,foreground}


%https://tex.stackexchange.com/a/349215
\tikzset{
    timeline/.style={arrows={}}%
    ,timeline style/.style={timeline/.append style={#1}}%
    ,year label/.style={font=\small\bfseries,below}%                  <-         removed \sffamily
    ,year label style/.style={year label/.append style={#1}}%
    ,year tick/.style={tick size=0pt}%
    ,year tick style/.style={year tick/.append style={#1}}%
    ,minor tick/.style={tick size=0pt, very thin}%
    ,minor tick style/.style={minor tick/.append style={#1}}%
    ,period/.style={solid,line width=\timelinewidth,line cap=square}%
    ,periodbox/.style={font=\small\bfseries,text=black}%              <-     removed \sffamily
    ,eventline/.style={draw,red,thick,line cap=round,line join=round}%
    ,eventbox/.style={rectangle,rounded corners=3pt,inner     sep=3pt,fill=red!25!white,text     width=3cm,anchor=west,text=black,align=left,font=\small}%
    ,tick size/.code={\def\ticksize{#1}}%
    ,labeled years step/.code={\def\yearlabelstep{#1}}%
    ,minor tick step/.code={\def\minortickstep{#1}}%
    ,year tick step/.code={\def\yeartickstep{#1}}%
    ,enlarge timeline/.code={\def\enlarge{#1}}%
    ,eventboxa/.style={eventbox,text width=#1,draw=A,fill=white}%
    ,eventboxb/.style={eventbox,text width=#1,draw=A,fill=none}%
}

% Still from %https://tex.stackexchange.com/a/349215
\newcommand*{\drawtimeline}[5][]{%
\def\fromyear{#2}%
\def\toyear{#3}%
\def\timelinesize{#4}%
\def\timelinewidth{#5}%
\pgfmathsetmacro{\timelinesizept}{\timelinesize}%
\pgfmathsetmacro{\timelinewidthpt}{\timelinewidth}%
\pgfmathsetmacro{\timelineoffset}{\timelinewidth/2}
\pgfmathsetmacro{\timelineoffsetpt}{\timelineoffset}
%
\begin{scope}[x=1pt, y=1pt, % Change main units to pt
    labeled years step=1,% Set some defaults
    minor tick step=0.25,%
    enlarge timeline=0cm,%
    year tick step=1,#1]
    \pgfmathsetmacro{\enlargept}{\enlarge}
    \pgfmathsetmacro{\yearticksep}{\timelinesize/((\toyear-    \fromyear)/\yeartickstep)}
    \pgfmathsetmacro{\minorticksep}{\timelinesize/((\toyear-\fromyear)/\minortickstep)}
    \pgfmathsetmacro{\minorticklast}{\minorticksep/\minortickstep}
    \foreach \y[remember=\y as \lasty (initially 0), count=\i from \fromyear] in {0,\yearticksep,...,\timelinesizept}{
        \coordinate (Y-\i) at (\y,0);
        \draw[year tick] (\y,-\ticksize/2) --  ++(0,\ticksize);
        \ifnum\i=\toyear\breakforeach\else
        \foreach \q[count=\j from 0] in {0,\minorticksep,...,\minorticklast}
        {
            \coordinate (Y-\i-\j) at (\q+\y,0);
            \draw[minor tick] (\q+\y,-\ticksize/2) -- ++(0,\ticksize);
        };\fi};%
    \pgfmathsetmacro{\nextyear}{int(\fromyear+\yearlabelstep)}
    \draw[timeline] (0,0) -- ++(-\enlargept,0) (0,0) -- ++    (\timelinesizept,0) coordinate (end) -- ++(\enlargept,0);% Timeline
    %    \foreach \y in {\fromyear,\nextyear,...,\toyear} \node[year label] at (Y-\y) {\y};
\end{scope}%

}
% Put a period identifier midway between the start and end of the period

% 1 = color of timeline segment
% 2 = period start
% 3 = period end
% 4 = period text

\newcommand{\period}[5]{\draw[period,#1] (Y-#2) -- (Y-#3)     node[periodbox,#5,midway,text=white] {#4};}


%This somewhat follows @cfr's Chronos. It was certainly inspired by Chronos.
%https://tex.stackexchange.com/a/349236
% 1 = format of line and box
% 2 = year 
% 3 = month
% 4 = day in month
% 5 = pin associated with starting coordinate (well suited to using polar     coordinate)
% 6 = branch at top of pin (well suited to using polar coordinate)
% 7 = Any extra formatting of node
% 8 = Name of node
% 9 = Node content

\newcommand{\vevent}[9]{
\pgfmathtruncatemacro{\syr}{#2}
\pgfmathtruncatemacro{\smth}{#3-1}
\pgfmathsetmacro{\dim}{#4/31}
\ifthenelse{#3=12}{%
    \pgfmathtruncatemacro{\fyr}{#2+1}
    \pgfmathtruncatemacro{\fmth}{0}
}{%
    \pgfmathtruncatemacro{\fyr}{#2}
    \pgfmathtruncatemacro{\fmth}{#3}
}
\draw[eventline,#1]($(Y-\syr-\smth)!\dim!(Y-\fyr-\fmth)$) -- ++(#5) -- ++(#6) node[#7] (#8) {#9};
}

% https://tex.stackexchange.com/questions/255298/draw-rectangular-nodes-defined-by-opposing-corner-coordinates-with-vertically-ce
\tikzset{
block/.style 2 args = {text = white,
    draw=none, inner sep=0, outer sep=0,
    rounded corners=3pt,
    fit=(#1) (#2)}
}

\newcommand{\fnode}[4][]{
\coordinate (bottom left) at (#2);
\coordinate (top right) at (#3);
\node[block={bottom left}{top right}, #1, label=center:#4] {};
}

\begin{document}

\begin{figure}[h]
\subfloat[Subcaption 1]{%
\begin{tikzpicture}
\drawtimeline[
labeled years step=1,
minor tick step=0.083333,
timeline style={draw=gray,line width=\timelinewidthpt},
minor tick style={-,lightgray,tick size=0pt,line width=0pt,yshift=-\timelineoffsetpt},
]%
{2017}{2019}{19cm}{0.5cm};
%
\period{A}{2017-0}{2017-1}{'17}{}
\period{B}{2017-1}{2017-2}{F}{}
\period{A}{2017-2}{2017-3}{M}{}
\period{B}{2017-3}{2017-4}{A}{}
\period{A}{2017-4}{2017-5}{M}{}
\period{B}{2017-5}{2017-6}{J}{}
\period{A}{2017-6}{2017-7}{J}{}
\period{B}{2017-7}{2017-8}{A}{}
\period{A}{2017-8}{2017-9}{S}{}
\period{B}{2017-9}{2017-10}{O}{}
\period{A}{2017-10}{2017-11}{N}{}
\period{B}{2017-11}{2017-12}{D}{}
\period{A}{2018-0}{2018-1}{'18}{}
\period{B}{2018-1}{2018-2}{F}{}
\period{A}{2018-2}{2018-3}{M}{}
\period{B}{2018-3}{2018-4}{A}{}
\period{A}{2018-4}{2018-5}{M}{}
\period{B}{2018-5}{2018-6}{J}{}
\period{A}{2018-6}{2018-7}{J}{}
\period{B}{2018-7}{2018-8}{A}{}
\period{C}{2018-8}{2018-12}{empty}{}
%
\begin{pgfonlayer}{background}
\vevent{A}{2017}{1}{10}{90:1cm}{45:0.5cm}{eventboxa=4cm,anchor=west}{H}{Start of ZoW consortium\\ \footnotesize 10-01-'17}
\vevent{A}{2017}{6}{8}{-90:2cm}{45:-0.5cm}{eventboxa=3cm,anchor=east}{H}{1\textsuperscript{st} Symposium\\ \footnotesize 8 Jun '17}
\vevent{A}{2017}{7}{20}{90:1cm}{45:0.5cm}{eventboxa=2.5cm,anchor=west}{H}{Completion of \\FPV systems\\ \footnotesize 20 Jul '17}
\vevent{A}{2017}{12}{14}{-90:2cm}{45:-0.5cm}{eventboxa=3cm,anchor=east}{H}{2\textsuperscript{nd} Symposium\\ \footnotesize 14 Dec '17}
\vevent{A}{2018}{1}{3}{90:2cm}{45:0.5cm}{eventboxa=2cm,anchor=west}{H}{Storm\\ \footnotesize 3 Jan '18}
\vevent{A}{2018}{1}{18}{90:1cm}{45:0.5cm}{eventboxa=2cm,anchor=west}{H}{Storm\\ \footnotesize 18 Jan '18}
\vevent{A}{2018}{6}{14}{-90:2cm}{45:-0.5cm}{eventboxa=3cm,anchor=east}{H}{3\textsuperscript{rd} Symposium\\ \footnotesize 14 Jun '18}
\end{pgfonlayer}
%
\coordinate (AA) at ([yshift=-1.6cm]$(Y-2018-1)!0.43!(Y-2018-2)$); % Bottom left
\coordinate (BB) at ([yshift=-0.6cm]$(Y-2018-7)!0.32!(Y-2018-8)$); % Top right
\fnode[text = white, fill=blue!50!white]{AA}{BB}{Internship}
\end{tikzpicture}
}

\subfloat[Internship period]{%
\begin{tikzpicture}
\drawtimeline[
labeled years step=1,
minor tick step=0.083333,
timeline style={draw=gray,line width=\timelinewidthpt},
minor tick style={-,lightgray,tick size=0pt,line width=0pt,yshift=-\timelineoffsetpt},
]%
{2018}{2019}{23cm}{0.5cm};
%
\period{A}{2018-0}{2018-1}{'18}{}
\period{B}{2018-1}{2018-2}{February}{}
\period{A}{2018-2}{2018-3}{March}{}
\period{B}{2018-3}{2018-4}{April}{}
\period{A}{2018-4}{2018-5}{May}{}
\period{B}{2018-5}{2018-6}{June}{}
\period{A}{2018-6}{2018-7}{July}{}
\period{B}{2018-7}{2018-8}{August}{}
\period{C}{2018-8}{2018-12}{empty}{}
%
\begin{pgfonlayer}{background}
\vevent{A}{2018}{3}{14}{90:1cm}{135:0.5cm}{eventboxa=3cm,anchor=east}{H}{AC box installed\\14  Mar '18}
\vevent{A}{2018}{3}{14}{-90:1cm}{45:-0.5cm}{eventboxa=3cm,anchor=east}{H}{New T4T ref. \\14  Mar '18}   
\vevent{A}{2018}{4}{20}{90:2cm}{135:0.5cm}{eventboxa=3cm,anchor=east}{H}{SP box installed\\14 Jun '18}
\vevent{A}{2018}{5}{15}{90:1cm}{135:0.5cm}{eventboxa=3cm,anchor=east}{H}{SP DC connected\\15 May '18}
\vevent{A}{2018}{6}{29}{90:2cm}{135:0.5cm}{eventboxa=3cm,anchor=east}{H}{T4T box installed\\29 Jun '18}
\vevent{A}{2018}{7}{9}{90:1cm}{135:0.5cm}{eventboxa=3cm,anchor=east}{H}{T4T DC connected\\9 Jul '18}        
\vevent{A}{2018}{6}{14}{-90:1cm}{45:-0.5cm}{eventboxa=3cm,anchor=east}{H}{3\textsuperscript{rd} Symposium\\14 Jun '18}

\end{pgfonlayer}

\end{tikzpicture}
}
\caption{Timelines}
\label{fig:timeline}
\end{figure}
\end{document}

The problem is that the labels of \subfloat are in the center of the figure, which is not the centre of the page (because the timeline has lots of whitespace). How do I force the labels to be in the center of the text margin?

Answer 1

You could set the bounding box of the tikzpictures manually with \useasboundingbox. To see what the bounding box currently looks like, you can add

\draw (current bounding box.north west) rectangle (current bounding box.south east);

right before \end{tikzpicture}.

With the help of that and some trial and error, you can find appropriate coordinates for the bounding boxes. For example

\useasboundingbox (0,-3) rectangle (15.9cm,2.8);

for the first one, and

\useasboundingbox (0,-2) rectangle (15.35cm,2.8);

for the second one.

After also adding \centering after \begin{figure} (and trimming the preamble down to something more minimal), I get

(The frames show the bounding boxes, as described above.)

Complete code:

\PassOptionsToPackage{table,dvipsnames,svgnames}{xcolor}
\documentclass[11pt, twoside, a4paper]{report}
\usepackage[inner = 30mm, outer = 20mm,  top = 30mm, bottom = 20mm,     headheight = 13.6pt]{geometry}
\usepackage{xifthen}
\usepackage{tikz}
\usetikzlibrary{calc,fit}
\usepackage[caption=false]{subfig}

\colorlet{A}{gray}
\colorlet{B}{lightgray}
\colorlet{C}{white}

\pgfdeclarelayer{background}
\pgfdeclarelayer{foreground}
\pgfsetlayers{background,main,foreground}


%https://tex.stackexchange.com/a/349215
\tikzset{
    timeline/.style={arrows={}}%
    ,timeline style/.style={timeline/.append style={#1}}%
    ,year label/.style={font=\small\bfseries,below}%                  <-         removed \sffamily
    ,year label style/.style={year label/.append style={#1}}%
    ,year tick/.style={tick size=0pt}%
    ,year tick style/.style={year tick/.append style={#1}}%
    ,minor tick/.style={tick size=0pt, very thin}%
    ,minor tick style/.style={minor tick/.append style={#1}}%
    ,period/.style={solid,line width=\timelinewidth,line cap=square}%
    ,periodbox/.style={font=\small\bfseries,text=black}%              <-     removed \sffamily
    ,eventline/.style={draw,red,thick,line cap=round,line join=round}%
    ,eventbox/.style={rectangle,rounded corners=3pt,inner     sep=3pt,fill=red!25!white,text     width=3cm,anchor=west,text=black,align=left,font=\small}%
    ,tick size/.code={\def\ticksize{#1}}%
    ,labeled years step/.code={\def\yearlabelstep{#1}}%
    ,minor tick step/.code={\def\minortickstep{#1}}%
    ,year tick step/.code={\def\yeartickstep{#1}}%
    ,enlarge timeline/.code={\def\enlarge{#1}}%
    ,eventboxa/.style={eventbox,text width=#1,draw=A,fill=white}%
    ,eventboxb/.style={eventbox,text width=#1,draw=A,fill=none}%
}

% Still from %https://tex.stackexchange.com/a/349215
\newcommand*{\drawtimeline}[5][]{%
\def\fromyear{#2}%
\def\toyear{#3}%
\def\timelinesize{#4}%
\def\timelinewidth{#5}%
\pgfmathsetmacro{\timelinesizept}{\timelinesize}%
\pgfmathsetmacro{\timelinewidthpt}{\timelinewidth}%
\pgfmathsetmacro{\timelineoffset}{\timelinewidth/2}
\pgfmathsetmacro{\timelineoffsetpt}{\timelineoffset}
%
\begin{scope}[x=1pt, y=1pt, % Change main units to pt
    labeled years step=1,% Set some defaults
    minor tick step=0.25,%
    enlarge timeline=0cm,%
    year tick step=1,#1]
    \pgfmathsetmacro{\enlargept}{\enlarge}
    \pgfmathsetmacro{\yearticksep}{\timelinesize/((\toyear-    \fromyear)/\yeartickstep)}
    \pgfmathsetmacro{\minorticksep}{\timelinesize/((\toyear-\fromyear)/\minortickstep)}
    \pgfmathsetmacro{\minorticklast}{\minorticksep/\minortickstep}
    \foreach \y[remember=\y as \lasty (initially 0), count=\i from \fromyear] in {0,\yearticksep,...,\timelinesizept}{
        \coordinate (Y-\i) at (\y,0);
        \draw[year tick] (\y,-\ticksize/2) --  ++(0,\ticksize);
        \ifnum\i=\toyear\breakforeach\else
        \foreach \q[count=\j from 0] in {0,\minorticksep,...,\minorticklast}
        {
            \coordinate (Y-\i-\j) at (\q+\y,0);
            \draw[minor tick] (\q+\y,-\ticksize/2) -- ++(0,\ticksize);
        };\fi};%
    \pgfmathsetmacro{\nextyear}{int(\fromyear+\yearlabelstep)}
    \draw[timeline] (0,0) -- ++(-\enlargept,0) (0,0) -- ++    (\timelinesizept,0) coordinate (end) -- ++(\enlargept,0);% Timeline
    %    \foreach \y in {\fromyear,\nextyear,...,\toyear} \node[year label] at (Y-\y) {\y};
\end{scope}%

}
% Put a period identifier midway between the start and end of the period

% 1 = color of timeline segment
% 2 = period start
% 3 = period end
% 4 = period text

\newcommand{\period}[5]{\draw[period,#1] (Y-#2) -- (Y-#3)     node[periodbox,#5,midway,text=white] {#4};}


%This somewhat follows @cfr's Chronos. It was certainly inspired by Chronos.
%https://tex.stackexchange.com/a/349236
% 1 = format of line and box
% 2 = year 
% 3 = month
% 4 = day in month
% 5 = pin associated with starting coordinate (well suited to using polar     coordinate)
% 6 = branch at top of pin (well suited to using polar coordinate)
% 7 = Any extra formatting of node
% 8 = Name of node
% 9 = Node content

\newcommand{\vevent}[9]{
\pgfmathtruncatemacro{\syr}{#2}
\pgfmathtruncatemacro{\smth}{#3-1}
\pgfmathsetmacro{\dim}{#4/31}
\ifthenelse{#3=12}{%
    \pgfmathtruncatemacro{\fyr}{#2+1}
    \pgfmathtruncatemacro{\fmth}{0}
}{%
    \pgfmathtruncatemacro{\fyr}{#2}
    \pgfmathtruncatemacro{\fmth}{#3}
}
\draw[eventline,#1]($(Y-\syr-\smth)!\dim!(Y-\fyr-\fmth)$) -- ++(#5) -- ++(#6) node[#7] (#8) {#9};
}

% https://tex.stackexchange.com/questions/255298/draw-rectangular-nodes-defined-by-opposing-corner-coordinates-with-vertically-ce
\tikzset{
block/.style 2 args = {text = white,
    draw=none, inner sep=0, outer sep=0,
    rounded corners=3pt,
    fit=(#1) (#2)}
}

\newcommand{\fnode}[4][]{
\coordinate (bottom left) at (#2);
\coordinate (top right) at (#3);
\node[block={bottom left}{top right}, #1, label=center:#4] {};
}

\begin{document}

\begin{figure}[h]
\centering % <-- added
\subfloat[Subcaption 1]{%
\begin{tikzpicture}
\useasboundingbox (0,-3) rectangle (15.9cm,2.8);
\drawtimeline[
labeled years step=1,
minor tick step=0.083333,
timeline style={draw=gray,line width=\timelinewidthpt},
minor tick style={-,lightgray,tick size=0pt,line width=0pt,yshift=-\timelineoffsetpt},
]%
{2017}{2019}{19cm}{0.5cm};
%
\period{A}{2017-0}{2017-1}{'17}{}
\period{B}{2017-1}{2017-2}{F}{}
\period{A}{2017-2}{2017-3}{M}{}
\period{B}{2017-3}{2017-4}{A}{}
\period{A}{2017-4}{2017-5}{M}{}
\period{B}{2017-5}{2017-6}{J}{}
\period{A}{2017-6}{2017-7}{J}{}
\period{B}{2017-7}{2017-8}{A}{}
\period{A}{2017-8}{2017-9}{S}{}
\period{B}{2017-9}{2017-10}{O}{}
\period{A}{2017-10}{2017-11}{N}{}
\period{B}{2017-11}{2017-12}{D}{}
\period{A}{2018-0}{2018-1}{'18}{}
\period{B}{2018-1}{2018-2}{F}{}
\period{A}{2018-2}{2018-3}{M}{}
\period{B}{2018-3}{2018-4}{A}{}
\period{A}{2018-4}{2018-5}{M}{}
\period{B}{2018-5}{2018-6}{J}{}
\period{A}{2018-6}{2018-7}{J}{}
\period{B}{2018-7}{2018-8}{A}{}
\period{C}{2018-8}{2018-12}{empty}{}
%
\begin{pgfonlayer}{background}
\vevent{A}{2017}{1}{10}{90:1cm}{45:0.5cm}{eventboxa=4cm,anchor=west}{H}{Start of ZoW consortium\\ \footnotesize 10-01-'17}
\vevent{A}{2017}{6}{8}{-90:2cm}{45:-0.5cm}{eventboxa=3cm,anchor=east}{H}{1\textsuperscript{st} Symposium\\ \footnotesize 8 Jun '17}
\vevent{A}{2017}{7}{20}{90:1cm}{45:0.5cm}{eventboxa=2.5cm,anchor=west}{H}{Completion of \\FPV systems\\ \footnotesize 20 Jul '17}
\vevent{A}{2017}{12}{14}{-90:2cm}{45:-0.5cm}{eventboxa=3cm,anchor=east}{H}{2\textsuperscript{nd} Symposium\\ \footnotesize 14 Dec '17}
\vevent{A}{2018}{1}{3}{90:2cm}{45:0.5cm}{eventboxa=2cm,anchor=west}{H}{Storm\\ \footnotesize 3 Jan '18}
\vevent{A}{2018}{1}{18}{90:1cm}{45:0.5cm}{eventboxa=2cm,anchor=west}{H}{Storm\\ \footnotesize 18 Jan '18}
\vevent{A}{2018}{6}{14}{-90:2cm}{45:-0.5cm}{eventboxa=3cm,anchor=east}{H}{3\textsuperscript{rd} Symposium\\ \footnotesize 14 Jun '18}
\end{pgfonlayer}
%
\coordinate (AA) at ([yshift=-1.6cm]$(Y-2018-1)!0.43!(Y-2018-2)$); % Bottom left
\coordinate (BB) at ([yshift=-0.6cm]$(Y-2018-7)!0.32!(Y-2018-8)$); % Top right
\fnode[text = white, fill=blue!50!white]{AA}{BB}{Internship}

\draw (current bounding box.north west) rectangle (current bounding box.south east);
\end{tikzpicture}
}

\subfloat[Internship period]{%
\begin{tikzpicture}
\useasboundingbox (0,-2) rectangle (15.35cm,2.8);
\drawtimeline[
labeled years step=1,
minor tick step=0.083333,
timeline style={draw=gray,line width=\timelinewidthpt},
minor tick style={-,lightgray,tick size=0pt,line width=0pt,yshift=-\timelineoffsetpt},
]%
{2018}{2019}{23cm}{0.5cm};
%
\period{A}{2018-0}{2018-1}{'18}{}
\period{B}{2018-1}{2018-2}{February}{}
\period{A}{2018-2}{2018-3}{March}{}
\period{B}{2018-3}{2018-4}{April}{}
\period{A}{2018-4}{2018-5}{May}{}
\period{B}{2018-5}{2018-6}{June}{}
\period{A}{2018-6}{2018-7}{July}{}
\period{B}{2018-7}{2018-8}{August}{}
\period{C}{2018-8}{2018-12}{empty}{}
%
\begin{pgfonlayer}{background}
\vevent{A}{2018}{3}{14}{90:1cm}{135:0.5cm}{eventboxa=3cm,anchor=east}{H}{AC box installed\\14  Mar '18}
\vevent{A}{2018}{3}{14}{-90:1cm}{45:-0.5cm}{eventboxa=3cm,anchor=east}{H}{New T4T ref. \\14  Mar '18}   
\vevent{A}{2018}{4}{20}{90:2cm}{135:0.5cm}{eventboxa=3cm,anchor=east}{H}{SP box installed\\14 Jun '18}
\vevent{A}{2018}{5}{15}{90:1cm}{135:0.5cm}{eventboxa=3cm,anchor=east}{H}{SP DC connected\\15 May '18}
\vevent{A}{2018}{6}{29}{90:2cm}{135:0.5cm}{eventboxa=3cm,anchor=east}{H}{T4T box installed\\29 Jun '18}
\vevent{A}{2018}{7}{9}{90:1cm}{135:0.5cm}{eventboxa=3cm,anchor=east}{H}{T4T DC connected\\9 Jul '18}        
\vevent{A}{2018}{6}{14}{-90:1cm}{45:-0.5cm}{eventboxa=3cm,anchor=east}{H}{3\textsuperscript{rd} Symposium\\14 Jun '18}

\end{pgfonlayer}
\draw (current bounding box.north west) rectangle (current bounding box.south east);
\end{tikzpicture}
}
\caption{Timelines}
\label{fig:timeline}
\end{figure}
\end{document}