Cockerels have to be dubbed by November of the year they hatch, but if they are old enough to show, they should probably be dubbed. And you don't dub the pullets.
Does it matter when they hatch? I always just put eggs into the incubator whenever I get them. Is there a certain time that you hatch them? Sorry I'm not a breeder.
Most birds need to be at least six months old to show; many breeds will not show well until quite a bir older than that. I guess you need to frame your questions better. What exactly are you wanting to know?