Mathematical manipulation of a pgf macro

I am trying to draw a TikZ diagram that I would like to start counting from zero instead of one. I have adapted this answer for my needs.

documentclass[tikz,border=3mm]{standalone}
usetikzlibrary{matrix}
begin{document}
begin{tikzpicture}[auto matrix/.style={matrix of nodes,
  draw,thick,inner sep=0pt,
  nodes in empty cells,column sep=-0.2pt,row sep=-0.2pt,
  cells={nodes={minimum width=1.9em,minimum height=1.9em,
   draw,very thin,anchor=center,fill=white,
   execute at begin node={%
   $vphantom{x_|}ifnumthepgfmatrixcurrentrow<4
     ifnumthepgfmatrixcurrentcolumn<4
      {#1}^{thepgfmatrixcurrentrow}_{thepgfmatrixcurrentcolumn}
     else 
      ifnumthepgfmatrixcurrentcolumn=5
       {#1}^{thepgfmatrixcurrentrow}_{N}
      fi
     fi
    else
     ifnumthepgfmatrixcurrentrow=5
      ifnumthepgfmatrixcurrentcolumn<4
       {#1}^{T}_{thepgfmatrixcurrentcolumn}
      else
       ifnumthepgfmatrixcurrentcolumn=5
        {#1}^{T}_{N}
       fi 
      fi
     fi
    fi  
    ifnumthepgfmatrixcurrentrowthepgfmatrixcurrentcolumn=14
     cdots
    fi
    ifnumthepgfmatrixcurrentrowthepgfmatrixcurrentcolumn=41
     vdots
    fi
    ifnumthepgfmatrixcurrentrowthepgfmatrixcurrentcolumn=44
     ddots
    fi$
    }
  }}}]
 matrix[auto matrix=z,xshift=3em,yshift=3em](matz){
  & & & & 
  & & & & 
  & & & & 
  & & & & 
  & & & & 
 };
 matrix[auto matrix=y,xshift=1.5em,yshift=1.5em](maty){
  & & & & 
  & & & & 
  & & & & 
  & & & & 
  & & & & 
 };
 matrix[auto matrix=x](matx){
  & & & & 
  & & & & 
  & & & & 
  & & & & 
  & & & & 
 };
 draw[thick,-stealth] ([xshift=1ex]matx.south east) -- ([xshift=1ex]matz.south east)
  node[midway,below] {$D$};
 draw[thick,-stealth] ([yshift=-1ex]matx.south west) -- 
  ([yshift=-1ex]matx.south east) node[midway,below] {joints};
 draw[thick,-stealth] ([xshift=-1ex]matx.north west)
   -- ([xshift=-1ex]matx.south west) node[midway,above,rotate=90] {time};
end{tikzpicture}
end{document}

This code has the following output.

I would like the index to begin from zero. Something like this.

I tried using the calc package to subtract from the thepgfmatrixcurrentrow and the thepgfmatrixcurrentcolumn like $thepgfmatrixcurrentrow - 1 = result$ but to no avail. Any help is greatly appreciated.

documentclass[tikz,border=3mm]{standalone}
usetikzlibrary{matrix}
begin{document}
begin{tikzpicture}[auto matrix/.style={matrix of nodes,
  draw,thick,inner sep=0pt,
  nodes in empty cells,column sep=-0.2pt,row sep=-0.2pt,
  cells={nodes={minimum width=1.9em,minimum height=1.9em,
   draw,very thin,anchor=center,fill=white,
   execute at begin node={%
   pgfmathtruncatemacro{nrow}{thepgfmatrixcurrentrow-1}%
   pgfmathtruncatemacro{ncol}{thepgfmatrixcurrentcolumn-1}%
   $vphantom{x_|}ifnumthepgfmatrixcurrentrow<4
     ifnumthepgfmatrixcurrentcolumn<4
      {#1}^{nrow}_{ncol}     
     else 
      ifnumthepgfmatrixcurrentcolumn=5
       {#1}^{nrow}_{N}
      fi
     fi
    else
     ifnumthepgfmatrixcurrentrow=5
      ifnumthepgfmatrixcurrentcolumn<4
       {#1}^{T}_{ncol}
      else
       ifnumthepgfmatrixcurrentcolumn=5
        {#1}^{T}_{N}
       fi 
      fi
     fi
    fi  
    ifnumthepgfmatrixcurrentrowthepgfmatrixcurrentcolumn=14
     cdots
    fi
    ifnumthepgfmatrixcurrentrowthepgfmatrixcurrentcolumn=41
     vdots
    fi
    ifnumthepgfmatrixcurrentrowthepgfmatrixcurrentcolumn=44
     ddots
    fi$
    }
  }}}]
 matrix[auto matrix=z,xshift=3em,yshift=3em](matz){
  & & & & 
  & & & & 
  & & & & 
  & & & & 
  & & & & 
 };
 matrix[auto matrix=y,xshift=1.5em,yshift=1.5em](maty){
  & & & & 
  & & & & 
  & & & & 
  & & & & 
  & & & & 
 };
 matrix[auto matrix=x](matx){
  & & & & 
  & & & & 
  & & & & 
  & & & & 
  & & & & 
 };
 draw[thick,-stealth] ([xshift=1ex]matx.south east) -- ([xshift=1ex]matz.south east)
  node[midway,below] {$D$};
 draw[thick,-stealth] ([yshift=-1ex]matx.south west) -- 
  ([yshift=-1ex]matx.south east) node[midway,below] {joints};
 draw[thick,-stealth] ([xshift=-1ex]matx.north west)
   -- ([xshift=-1ex]matx.south west) node[midway,above,rotate=90] {time};
end{tikzpicture}
end{document}

documentclass[tikz,border=3mm]{standalone}
usetikzlibrary{matrix}
begin{document}
begin{tikzpicture}[auto matrix/.style={matrix of nodes,
  draw,thick,inner sep=0pt,
  nodes in empty cells,column sep=-0.2pt,row sep=-0.2pt,
  cells={nodes={minimum width=1.9em,minimum height=1.9em,
   draw,very thin,anchor=center,fill=white,
   execute at begin node={%
   $vphantom{x_|}ifnumthepgfmatrixcurrentrow<4
     ifnumthepgfmatrixcurrentcolumn<4
      {#1}^{thenumexprpgfmatrixcurrentrow-1}_{thenumexprpgfmatrixcurrentcolumn-1}
     else 
      ifnumthepgfmatrixcurrentcolumn=5
       ,{#1}^{thenumexprpgfmatrixcurrentrow-1}_{N}
      fi
     fi
    else
     ifnumthepgfmatrixcurrentrow=5
      ifnumthepgfmatrixcurrentcolumn<4
       {#1}^{T}_{thenumexprpgfmatrixcurrentcolumn-1}
      else
       ifnumthepgfmatrixcurrentcolumn=5
        ,{#1}^{T}_{N}
       fi 
      fi
     fi
    fi  
    ifnumthepgfmatrixcurrentrowthepgfmatrixcurrentcolumn=14
     cdots
    fi
    ifnumthepgfmatrixcurrentrowthepgfmatrixcurrentcolumn=41
     vdots
    fi
    ifnumthepgfmatrixcurrentrowthepgfmatrixcurrentcolumn=44
     ddots
    fi$
    }
  }}}]
 matrix[auto matrix=z,xshift=3em,yshift=3em](matz){
  & & & & 
  & & & & 
  & & & & 
  & & & & 
  & & & & 
 };
 matrix[auto matrix=y,xshift=1.5em,yshift=1.5em](maty){
  & & & & 
  & & & & 
  & & & & 
  & & & & 
  & & & & 
 };
 matrix[auto matrix=x](matx){
  & & & & 
  & & & & 
  & & & & 
  & & & & 
  & & & & 
 };
 draw[thick,-stealth] ([xshift=1ex]matx.south east) -- ([xshift=1ex]matz.south east)
  node[midway,below] {$D$};
 draw[thick,-stealth] ([yshift=-1ex]matx.south west) -- 
  ([yshift=-1ex]matx.south east) node[midway,below] {joints};
 draw[thick,-stealth] ([xshift=-1ex]matx.north west)
   -- ([xshift=-1ex]matx.south west) node[midway,above,rotate=90] {time};
end{tikzpicture}
end{document}