I got some keets about 5 weeks ago when they were must one week old. The will turn 6 weeks this Saturday. I have built them a chicken coop and was wondering if 6 weeks is enough to move them out of the large (48x48x48) cardboard box and into the coop. I live in TN so it does not get terribly cold and I have a heat lamp I am planning on mounting on the inside of the hen house. Would they be okay?