Here is the kind of thing I think you want although I'm not sure. You can fiddle with the sizes to make the most of the space but you need things smaller than in the MWE unless you want more than 2 lines of sub-figures which is another option.
\documentclass[a4paper, 12pt]{article}
\usepackage[left=3cm, right=2cm, top=3cm, bottom=4cm]{geometry}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
%Graphs and Diagrams
%\usepackage{subgraphic}
\usepackage{subfig}
\usepackage[demo]{rotating} %remove 'demo' option for real file
\usepackage{float}
\usepackage[labelsep=newline,% line break after label
justification=centering,
singlelinecheck=off, font=bf]{caption}
\makeatletter% Set distance from top of page to first float
\setlength{\@fptop}{5pt}
\long\def\@makefigcaption#1#2{%
\vskip\abovecaptionskip
\footnotesize\textbf{#1.} \footnotesize#2
\ifdim \wd\@tempboxa >\hsize
\textbf{#1.} #2\par
\else
\global \@minipagefalse
\hb@xt@\hsize{\hfil\box\@tempboxa\hfil}%
\fi
\vskip\belowcaptionskip}
\renewcommand{\figure}{\let\@makecaption\@makefigcaption\@float{figure}}
\makeatother
\begin{document}
\section{Appendix}
\centering
\begin{figure}[h]
\begin{turn}{90}
\begin{minipage}{.75\textheight}
\subfloat[DSUE1 $-$ Full Sample]{\includegraphics[width=0.225\textheight]{aasc_full_dsue1.eps}\label{fig:fullDSUE1}} \quad
\subfloat[DSUE2 $-$ Full Sample]{\includegraphics[width=0.225\textheight]{aasc_full_dsue2.eps}\label{fig:fullDSUE2}}\quad
\subfloat[DSUE3 $-$ Full Sample]{\includegraphics[width=0.225\textheight]{aasc_full_dsue3.eps}\label{fig:fullDSUE3}} \quad
\subfloat[DSUE1 $-$ Pre-Crisis]{\includegraphics[width=0.225\textheight]{aasc_precrisis_dsue1.eps}\label{fig:preDSUE1}} \quad
\subfloat[DSUE2 $-$ Pre-Crisis]{\includegraphics[width=0.225\textheight]{aasc_precrisis_dsue2.eps}\label{fig:preDSUE2}}\quad
\subfloat[DSUE3 $-$ Pre-Crisis]{\includegraphics[width=0.225\textheight]{aasc_precrisis_dsue3.eps}\label{fig:preDSUE3}} \quad
\end{minipage}
\end{turn}
\end{figure}
\end{document}
Update
To move the figure downwards, you can insert some vertical space before and after, followed by a \clearpage
:
\documentclass[a4paper, 12pt]{article}
\usepackage[left=3cm, right=2cm, top=3cm, bottom=4cm]{geometry}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
%Graphs and Diagrams
%\usepackage{subgraphic}
\usepackage{subfig}
\usepackage[demo]{rotating} %remove 'demo' option for real file
\usepackage{float}
\usepackage[labelsep=newline,% line break after label
justification=centering,
singlelinecheck=off, font=bf]{caption}
\makeatletter% Set distance from top of page to first float
\setlength{\@fptop}{5pt}
\long\def\@makefigcaption#1#2{%
\vskip\abovecaptionskip
\footnotesize\textbf{#1.} \footnotesize#2
\ifdim \wd\@tempboxa >\hsize
\textbf{#1.} #2\par
\else
\global \@minipagefalse
\hb@xt@\hsize{\hfil\box\@tempboxa\hfil}%
\fi
\vskip\belowcaptionskip}
\renewcommand{\figure}{\let\@makecaption\@makefigcaption\@float{figure}}
\makeatother
\begin{document}
\section{Appendix}
\vfill
\centering
\begin{figure}[h]
\begin{turn}{90}
\begin{minipage}{.75\textheight}
\subfloat[DSUE1 $-$ Full Sample]{\includegraphics[width=0.225\textheight]{aasc_full_dsue1.eps}\label{fig:fullDSUE1}} \quad
\subfloat[DSUE2 $-$ Full Sample]{\includegraphics[width=0.225\textheight]{aasc_full_dsue2.eps}\label{fig:fullDSUE2}}\quad
\subfloat[DSUE3 $-$ Full Sample]{\includegraphics[width=0.225\textheight]{aasc_full_dsue3.eps}\label{fig:fullDSUE3}} \quad
\subfloat[DSUE1 $-$ Pre-Crisis]{\includegraphics[width=0.225\textheight]{aasc_precrisis_dsue1.eps}\label{fig:preDSUE1}} \quad
\subfloat[DSUE2 $-$ Pre-Crisis]{\includegraphics[width=0.225\textheight]{aasc_precrisis_dsue2.eps}\label{fig:preDSUE2}}\quad
\subfloat[DSUE3 $-$ Pre-Crisis]{\includegraphics[width=0.225\textheight]{aasc_precrisis_dsue3.eps}\label{fig:preDSUE3}} \quad
\end{minipage}
\end{turn}
\end{figure}
\vfill
\clearpage
New page
\end{document}
Update II
As requested, here is a way to customise the captions for figures and tables:
\documentclass[a4paper, 12pt]{article}
\usepackage[left=3cm, right=2cm, top=3cm, bottom=4cm]{geometry}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
%Graphs and Diagrams
%\usepackage{subgraphic}
\usepackage{subfig}
\usepackage[demo]{rotating} %remove 'demo' option for real file
\usepackage{float}
\usepackage[labelsep=newline,% line break after label
justification=centering,
singlelinecheck=off, font=bf]{caption}
\makeatletter% Set distance from top of page to first float
\setlength{\@fptop}{5pt}
\long\def\@makefigcaption#1#2{%
\vskip\abovecaptionskip
\footnotesize\textbf{#1.} \footnotesize#2
\ifdim \wd\@tempboxa >\hsize
\textbf{#1.} #2\par
\else
\global \@minipagefalse
\hb@xt@\hsize{\hfil\box\@tempboxa\hfil}%
\fi
\vskip\belowcaptionskip}
\renewcommand{\figure}{\let\@makecaption\@makefigcaption\@float{figure}}
\makeatother
\DeclareCaptionLabelFormat{my-figures}{%
\def\tempa{figure}%
\def\tempb{#1}%
\ifx\tempa\tempb(\textbf{#2})\else{\centering(\textbf{#2})}}
\captionsetup{labelformat=my-figures,labelsep=quad}
\begin{document}
\section{Appendix}
\vfill
{\centering
\begin{figure}[h]
\begin{turn}{90}
\begin{minipage}{.75\textheight}
\subfloat[DSUE1 $-$ Full Sample]{\includegraphics[width=0.225\textheight]{aasc_full_dsue1.eps}\label{fig:fullDSUE1}} \quad
\subfloat[DSUE2 $-$ Full Sample]{\includegraphics[width=0.225\textheight]{aasc_full_dsue2.eps}\label{fig:fullDSUE2}}\quad
\subfloat[DSUE3 $-$ Full Sample]{\includegraphics[width=0.225\textheight]{aasc_full_dsue3.eps}\label{fig:fullDSUE3}} \quad
\subfloat[DSUE1 $-$ Pre-Crisis]{\includegraphics[width=0.225\textheight]{aasc_precrisis_dsue1.eps}\label{fig:preDSUE1}} \quad
\subfloat[DSUE2 $-$ Pre-Crisis]{\includegraphics[width=0.225\textheight]{aasc_precrisis_dsue2.eps}\label{fig:preDSUE2}}\quad
\subfloat[DSUE3 $-$ Pre-Crisis]{\includegraphics[width=0.225\textheight]{aasc_precrisis_dsue3.eps}\label{fig:preDSUE3}} \quad
\caption{Figure Caption}
\end{minipage}
\end{turn}
\end{figure}}
\vfill
\clearpage
\begin{table}
\centering
\begin{tabular}{cc}
A & table\\
\end{tabular}
\caption{Table Caption}
\end{table}
\end{document}
Best Answer
From looking at
rotating.sty
, I believe this happens becausesidewaysfigure
puts the contents in a floating box whose size is\textheight
. With the section heading on the page, there is insufficient space remaining on the page to place a\textheight
sideways figure. This causes thesidewaysfigure
to float to the next page.The solution, I suggest, is don't use a float, which means don't use
sidewaysfigure
. Anadjustbox
can be used here. I put the two figures centered horizontally using the center key ofadjustbox
and vertically using\vspace*{\fill}
at the top and bottom of the page content.This is the result:
This is the MWE: