x2 They will be about 2 weeks when they start to come in (and get ugly) and about 10-12 weeks when they lose the last of their fluff. The tips of the wings will be the first to feather and their "arm pits" and vent area will be the last.
ETA: on my last batch I would pick the bits of down that stuck on the end of the feathers off and my little white giant cockerl seemed to enjoy it, lol