Babies suckle from their mother at least for four weeks, although she will reduce the quantity and quality of her milk as they start to eat solid food. They can be weaned at four weeks. In high-level commercial rabbitries, all babies are weaned at four weeks because their mothers will have been re-mated within a couple of days of their birth.
Depending on your individual breeding style and feeding method, I do not recommend such early weaning. I prefer to remate only at two to three weeks after birth if the doe is in prime condition. Her babies are then weaned at six weeks. Those extra two weeks with their mother gives the young stock time to learn from mom and become confident strong youngsters.
Stock weaned too young is often very stressed and stress is a major cause of rabbits dying. Stressed babies are also more likely to contract various diseases.
At weaning, sex all the babies, mark them - with a koki pen - where possible and split the does from the bucks (male rabbits). Bucks and does from two or three litters can now be placed in growing pens or colony pens until they are ready for selection for either future breeding stock, sale stock or slaughter stock.
Be sure that you sex correctly. Mixed units fight more than single-sex units and one buck in a doe colony can get very active from 4 months of age and a string of unexpected litters could arrive.