That's a pretty rare thing to happen since most mother chins won't attack any of their little ones.
I haven't weaned a kit under 8 weeks in recent memory. It's better for a kit to nurse as long as possible to get that little bit of extra immune system help.
When there is a good reason to wean early, that's fine. However, I have seen MANY MANY backyard breeders that will wean as early as possible in order to sell their kits and make money. That should never even factor into the equation. When I hear about people regularly weaning kits early I automatically start thinking that it's because they want the cash for the chins sooner. I'm not saying that everyone does that, but around here I've seen it happen many times and often the health of the kits suffer because someone couldn't just wait a few more weeks.