I do a hard stop at the the end of 4 weeks which is basically when they have their eyes open and can move around without wobbling too bad. If you leave them with the mom after that they will be lazy and nurse rather than eat on their own - this takes a lot of energy out of the mom and they don't 'last' as long as breeders.
Another thing I would caution that I found out the hard way was do not keep anything that is nursing in any way with a mom that is about to give birth. I don't need to give details, just trust me. Don't do that.





