Not wishing to contradict anyone (would I???), I think it could depend on the breed. I keep Light Sussex, Welsummers and Araucanas and my lads don't start crowing till they're about 20-plus weeks old. Your hens won't be laying yet, either - they're too young. I usually reckon on about 26 weeks before they come into lay properly. (It's very difficult to type this, as I've got a small kitten trying to climb on my shoulder at the moment & snuggle into my shirt to hide from the other cats...!!)