It really is so much easier when you have more than one to look at. Then the differences are pretty obvious (for about 95%, there are always a few that you can't tell for a while yet). Last year I had one cockerel that I moved about every week to the pullet pen, then back to the cockerel pen....finally could figure out that he was a he and not a she. He eventually went into the cull pen since he obviously didn't have the type I was looking for.