Usually by 4 or 5 months you can usually tell what they are. The cockerels will begin to get long, silkie, wispy feathers on the neck and tail. If the tail and neck feathers appear to be rounded out then it's probably a pullet. Also, the cockerels develop a much bigger and brighter comb then the pullets earlier. And the cockerels get signs of spurs pretty early on too. Also, not all the time but most of the time for me, the personality of the bird helps you tell. The cockerels are usually much more outgoing and will be more likely to come up to you or let you hold them. The pullets will be more skittish towards you. Cockerels also stand more upright and tend to peck the others or try to start stuff with other birds. Also, welcome btwHi there. I have had the standard red laying hens for the past 5 years now and wanted to do something different. So this year we actually incubated 2 batches of fertilized eggs. We have 3 black chanteclercs chicks that are 12 weeks old and 7 black chanteclercs chicks that are 8 weeks old. I think there are some chicks that are obviously roosters but would like to know how early you can identify the males from the females.