What breed are you raising?
If these are Bobwhites, they won't be mature for 6+ months. So they are far easier to mix together at young ages. 1 1/2 to 2 weeks in a cage next to the older birds should be enough. Everybody sees, nobody touches. Generally young birds mix fair enough. You don't have to worry about any hormonal aggression until next spring.
Coturnix mature up fast, so not so easy. Keep the new birds in the same way, in a cage or sectioned off area of your pen right next to the older flock. Leave them this way for 3 weeks. Be very mindful when you mix them all together. If it turns bloody, always intervene. Make sure to keep your ratio of male to female proper and don't mix in two males together.