Leaving the Nest...

No, wait until at least 8 or 10 weeks please.

They still have so much to learn at 6 weeks, 12 weeks is best. 

http://www.breedlist.com/faq/young.html

some places have laws about the minimum age too

If tey leave mama too early it can lead to behaviour problems later, such as biting and scratching during play. Mother cats kinow just how to discipline their kittens so they are socilaised and well mannered with other cats and with people, and it can be hard for new owners to be as effective. They will be better adjusted too to leaving her and not crying so much if they are bit older. So if you possibly can, leave them till 10 weeks. Most breeders wait till at least three months. But every week helps.

jennyranson said:

If tey leave mama too early it can lead to behaviour problems later, such as biting and scratching during play. Mother cats kinow just how to discipline their kittens so they are socilaised and well mannered with other cats and with people, and it can be hard for new owners to be as effective. They will be better adjusted too to leaving her and not crying so much if they are bit older. So if you possibly can, leave them till 10 weeks. Most breeders wait till at least three months. But every week helps.

Click to expand...

Know why so many people have crazy, neurotic cats? Mostly because they were taken away from their mamas and littermates (IMO, the littermates are most important) too young. It can cause some serious problems. Even 8 weeks is too young, IMO, 9 weeks is bare minimum. 10 to 12 is ideal. They'll be much better kitties for their new owners.

---iLoveKitties said:

Can kittens be given away to good homes when they are 6 weeks? Or should I wait longer?

Click to expand...

Longer, of course. the 6-8 weeks was when I was young... it was said they wouldnt bound properly otherwise.  But we know it isnt true. Possibly not even true for dogs, definitely not for kittens. They bound just fine if you are kind and friendly to them, at any age.

My hypothesis the tale of 6-8 weeks were from the time very few people had pure inside cats, looking on humans as their Ma or Pa.

Yes, taking in essentially semiferale barn cats, it makes some sense to take them when they are 6 weeks, if you want to socialize them without any trouble.

But it is not recommendable with already socialized homecats no.