The time to separate the kittens is as early as possible. By 8 weeks they have already had a number of lessons from mum -- chief amongst them being that humans are the enemy even if they feed you. The other lessons are how to climb a tree or fence, how to balance on very thin edges (good for running away), the rudiments of how to hunt (even if the only stuff available is cockroaches and spiders), how not to approach dogs, etc. Unfortunately, I have never seen a mother cat teach her youngsters how to cross a street safely.
In my experience, it takes anywhere from 5 months to a year to get a truly ferel cat to permit touching, after mama has taught her aversion-to-humans-and-other-dangerous-beasts-lessons. If you have homes for ferel kittens, the best thing for everyone is to try to intice the kittens to you by placing food for the mother and her kittens further and further away from their actual nest. Don't go near the nest, as most mother cats will immediately move their kittens to another venue.
You start with food in several saucers right near the nest, then move it further and further until it is quite far away. This gives you the opportunity to observe if the kittens are being cared for by their mother, or if she is playing favorites and neglecting one or more of them. I had one ferel mother who was white. She took excellent care of her two white kittens, but totally ignored the one that was grey with white underparts. She didn't shove it away, but she didn't clean it very often, didn't seem to care if it nursed or not, and when she started to train her youngsters to hunt, often just went off with the other two at a moment when the gray and white kitten was asleep. She was, in effect, color biased -- something I thought confined to the human animal.
Accordingly, I set out extra food for the gray, and entertained it with dingly balls and the like when the mother was off with the other two. The gray became quite domesticated for a ferel, but went off on her own at 6 months, only coming back occasionally to scavange food. I could pat her briefly if she wanted the contact, but otherwise she was untouchable. One of the white kittens I simply kidnapped and gave to a neighbor at 8 weeks, and it became an excellent family member (but was killed by a dog at age two). The other white went off with her mother, and both came back once in a while for a few months to eat and then I never saw them again. They were both totally violent about touching. I did trap all of them at one time or another (the kits were all females), and had them spayed and vaccinated, so that at least freed them from that problem.
The best adoption time is 6-8 weeks -- after that, bonding is usually superficial and based on whether they like the food you give them. What you want is a cat who will bond with a human family. That is difficult to do if the cat has been trained to be ferel by its mother. If they do bond, they become completely loyal and integrated into their family. My 14 in-house cats are all bonded, as I am to them. It is interesting to see their interactions with the dogs in the house (4) -- to whom the look for protection from dangers and alarms, and for a big warm body in the winter. The dogs have their favorite cats, with whom they often sleep, sometimes trading off cleaning chores. The ferels sadly bond with no one -- cat or human -- and make only casual companionships of convenience. So I don't really think that I am disrupting their "natural" rights. None of use are wholly what we were born to be -- in a multi-species household, we accomodate each other and learn from each other, the cats learning some of the dog tricks to fight and play, and the dogs learning cat tricks. I learn both, and they learn my moods and rules. We compromise, tolerate, and develope individual and group friendships, and thus create a real family. I think its a process that might be applied to the various peace efforts here and in other parts of the world. The cats are still cats, the dogs still dogs, and I am still human, and when we are exclusively with our own, we behave more true to form, but when we are together, we have family traditions, family rules, and family jokes. It is really something to see.
Hope this is helpful.
Peace, Catherine