That might add up tp 8 weeks, but the key is that the kittens were weaned and no longer nursing. It is suppose to be 2 weeks AFETR they stop nursing. But don't be in a hurry to wean them, if mom lets them then it's OK. The longer they are with her the better off in the long run they will be. On the other hand, some moms FORCE their babies to stop early. It is a woman's right to choose, I guess.