Using laser engraving for date stamping
G-code is vector based positioning. You can work in relative or absolute moves (I suggest the latter). 

If you want to generate characters you'll need to find a vector (stroke) font you like and convert date text (from somewhere, the Arduino has no real-time clock) to G-code and then run a G-code interpreter to control the steppers and laser module.  

Date information-> Date text -> Character movements for entire text-> G-code -> G-code interpreter-> Hardware