My RIR roo has been crowing since about 5 weeks? He is now about 14 weeks and crows constantly.
My JG roo has never crowed. He is about 12.5 weeks. He is kept separately during the day but he and my RIR were in a shared (but separated by fencing) shed at night for a few months. They have only moved into separate night quarters for a week now and I caught my JG crowing yesterday. Sounds more like honking, but he is at least attempting it.