Can't see the comb all that clearly - for a bird of that age I would expect a Delaware cockerel to have a much more prominent comb as they are single combed. Can you get a clear shot of the comb, or tell us what type of comb the bird has? The columbian pattern shows up in several breeds.
He should get larger. How large depends on his breed. By the time a bird is 5-6 months old, it is usually around it's adult size. However, slower maturing breeds like Cochins and Brahmas take longer.