I just put mine outside three days ago at just over two and a half weeks. Mind you they are in a small chicken barn with a brooder light but they were pooping all over my house and I could no longer contain them....I miss them terribly even though they are only 50 feet from the house.I let mine outside at 12 weeks. I was told that before that they don't have a great internal temperature regulation. Of course, it was cold here then, so I was more worried. If it was during a season when it was actually WARM I would be happy to let them out as soon as they were feathered I think!