I ordered some Delaware chicks this spring, and wanted 1 rooster in the order. The first order took 5 days to reach me, only two chicks survived that ordeal. The company reshipped replacement chicks, again, with one rooster. These reached me on time, but 1 chick died when I'd had them a week. So I have two 13 week old birds and a group of 9 week old birds, and still cannot tell if any are roosters. At what age can you start tell roosters from pullets in this breed? Thanks!