How To Change xy Home Position?

I need to change the xy home position for the hot end. I need to move it back in the y-direction about 13mm which means I will need to move the bed 13mm forward from its stock default home position when homing. Any idea on how to do this?

In case anyone is wondering, the following gcode will home the hot end to x=0, then y=+12, then z=0:

G90 ;absolute positioning
G1 F1500 ; axes movement rate = 25mm/sec
G28 X ;home x
G28 Y ;home y
G1 Y12 ;move Y+12 so hot end doesn’t hit the bed clips when z homes
G1 F150 ;slow movement rate down to 2.5mm/sec for Z axis
G28 Z ;home z

If saving on an SD card make sure to hit the enter key after the last line before saving the file so it gets executed.