between 6 weeks and 12 weeks for splitting them up, whenever mum says she's had enough, just watch her closely if she starts chasing the babies thats the time to remove her - for hutched rabbits its best to remove the mum during the day and return her at night from 6 weeks onwards as it prevents her getting too stressed... if they're in a large enough space mum can stay with them permamently (although she'll apprechiate a space to get away from them, a nice high ish ledge or house that the babies cant get up onto. Male babies need to be removed by 12 weeks, does can stay permamently if you're planning on keeping them theres no need to split them at all...
They will be weaned by now (weaning is simply when they are no longer dependant on milk) which is normally 4 weeks, although many will continue to drink longer, mums milk starts to dry up from that point and their main diet comes from solid foods.
ETA: just re-red your last post and saw that they had homes to go to, sorry... tbh 8 weeks is too young to rehome, its too risky for them, 10 weeks for larger buns and 12 for small is the best indicator, they will need to have been living independantly from mum for a full 2 weeks prior to leaving (that two week period is also a good time to get them vaccinated and given some mite preventative and wormer)
at 6 weeks they no longer need mum to survive, just to learn behaviors from (things like using a bottle are learnt from mum), I would suggest removing mum during the day and using that time to give them extra handling and attention to ensure they don't pick up her bad behavior, and probably remove mum in a week, if they appear to be fit well and doing bunny things (using a litter tray, water bottle etc)