it depends on the individual, like.. a lot of people can tell around 5 weeks old, some at a month, some at a few weeks.. Like a batch of American games i just had hatch off... Two are for sure cocks since they're already getting red in their combs, fair size feet, tail's held straight up, they stand tall, less scared of people, etc etc.. they are two weeks now. Some you can tell from birth if they are sexlinks.
But usually, the average to tell is anywhere from 4-5 months, start looking for signs around 2 months if you can't tell now.
Get pictures and people will give you plenty of help on guessing the breeds, genders, etc.
-Daniel
