If you mean when will he crow, well it could be anytime from 4 weeks old to 6 months or even more.
If you mean when will he get 'rooster feathers', that could again start very young, at this age, or only start around 6 months.
If you mean when will he start mating, that could start at 4 weeks or after 6 months.
And all of these developments could start at any times inbetween those ages. A LOT depends on diet, environment, family strain, etc, even more so than on breed.
6 months is the average point, I think, at which most male chickens of any breed, environment, diet, family strain, etc have begun to definitively show themselves as males.
If you mean when will he be his adult size and development, at 12 months he should be almost completely 'done', but most males do continue to grow slightly into their second year, generally putting on more bulk than height.
You're welcome. If you want a better opinion, as in a more exact one, post a pic of him, and people will have a better idea by observing his level of development. Otherwise all one can offer is generalizations. Not much help, I know.