It's not recomended to weane kits early, it makes them far more prone to all kinds of deseases and makes them very vulnerable to early death. I keep my kits with their moms until they sell or get big enough for chopping at 3months or so.
When I do decide to split the mom and kits it'll be at 5 weeks minimum ideally, 2 months minimum for my english angoras.
There are always exeptions, maybe the mom died, maybe she has too many kits and some need to be removed or maybe one devellopped a health issue that needs treatment and cant stay in with the others. The youngest I've chosen to weane at is 3 weeks because of a severe eye infection that needed hourly treatment and I would highly recomend doing all you can to keep them that long agaisnt all odds if you can manage. At 3 weeks They've already started eating hay naturally so even if they're not weaned yet, it's easier to do at this point. Before that, you'll have issues, at 2 weeks or less they arent strong enough to chew the food and can't drink water by themselves yet. They are 100% on milk at this time wich means you'd have to feed them formula somehow or risk losing half the litter.
My first year of breeding I've had a mom die, leaving her 2 week olds and neither me or my friend had another female that could adopt or any formula available. I managed to get them to eat apples, they were easier to chew and juicy so they didnt lack fluids that way. But they grew slower and I ended up losing a few kits to malnourishment. Even at 3 weeks they hadnt started eating hay, I managed to add carrots and lettuce to their diets but that was it. I ended up taking a young 6week old male I bought and placing him with them. They loved him and always swarmed him (see my avatar) and they finally learned to eat hay after following his exemple.
Finally, I've had petshop suppliers force me to weane at 4 weeks cause they needed the bunnies to be smaller to sell and I hated that. He didnt care about their welfare, just about profit. From my perspective, 5 weeks is the best timing for most thougher breeds, while more fragile ones like english angoras need 2 months.