Kits 4 to 8 week old will eat drink poop and pee on their own, thats not the issue with weaning them so early.
the issue is they need the cecal product mother leaves for them to digest the feed material. babys sometimes do not transition off milk to pellets well, it used to be called mucoid enteritis but its mucoid toximia now. It will kill the babys that were weaned too soon, but not every kit.
be sure to have hay for them to chew on so their digestive system will be cleaned out.
Most States mandate no Kittens puppys,rabbits can be sold before the age of 8 weeks old.
Its unfortunate most pet stores want rabbits at 4 to 6 weeks old because of the cute factor.
every rabbit that small is a netherland dwarf untill you get it home and it grows up to be a 10 lb rabbit.