Kittens should stay with their mother until they are 8 weeks old. The longer a kitten stays with her mother, the more socialized and well developed she will be.
Kittens don't open their eyes for 7 to 10 days after they're born. They have poor vision until they are around 10 weeks of age, and at that time, they will be able to see as well as adult cats. Kittens are weaned from around 3 weeks of age. The transition from mother's milk to solid food takes from 3 to 4 weeks. The weaning process should be completely handled by the mother cat.
The time a kitten spends with her mother is very important to the kitten's development. The mother will teach the kitten how to behave and how to be a social creature. This is extremely important for a well-rounded, confident pet.