If you use G92 to set Z to zero, make sure that you allow the Z axis to go negative by more than you will need to cut, or set it to the minimum depth. The firmware by default won't allow the axis to go negative, so you will get an error "out of limits" and your gcode will abort when you try to plunge into the work.
You'll also want to allow negative movement in the X and Y axes as well, since most CAM software sets the 0,0 point as the outside of whatever shape you're cutting and will want to go negative by at least 1/2 your tool diameter at some point.