Best time for introducing new males is right after the males have molted their tails. Their aggression is lowest at this point. They will fight, at least to establish pecking order.
Some males will be able to tolerate other males, as long as none of them try to upset the 'balance' of the pecking order. Some males, no way, never ever will tolerate another male. Ever.
Another good way of introducing males into a flock is getting young males- yearlings or younger. More males tolerate these... and again, as long as the younger males don't challenge the older male(s), there can be a balance of sorts. But some young males DO eventually get saucy with age and try to fight their way up the dominance ladder, that will cause a big mess, especially if all are confined.
Basically it's kind of you never know for sure until trying it. If it's possible to keep them separated, it's the best- no unpleasant surprises that way...
Good luck and congrats on getting new birds!