My cockerels were separated from the pullets at 3 mo old and added to my main flock until the pullets were old enough to lay .They stayed with them until one was 'mature' enough to be 'accepted' by my older hens(6 more months) Only one of my roosters is calm enough to be released in the main...
Since I divided my flock in half and gave each their own hens my flocks calmed down .They all seem to be much happier. I don't have aggressive roosters but I didn't overreact to a few pecks on the foot when they were younger. One of my favorite hens walked up and pecked me on the leg yesterday lol