My wife and I are thinking about getting 3 more chicks to add to our flock of 7 so I have been wondering the same thing. The general rule seems to be 5-8 weeks when there feathers grow in. Knowing where you are, the expected weather HOT! I would suspect they will be fine.
We also have a buff, about 6 month old, started laying about a month ago. She has been acting egg bound so we have given her two warm baths, and she just passed a large poop, the first seen by us in two days! hope that was it. This site has been a great help. At least we feel like were doing...