I agree that it's best to separate with fencing or wire for a couple of weeks. The idea is that the older birds and the new ones can see each other but not get to each other. There will be less pecking and chasing when you finally let them together.
I normally don't let them together until the young ones are almost the size of the adults. It shouldn't be too much longer for you. I don't intergrate them until I can put the chicks into the coop at night. I find it easier to train them to go into the adult coop when they are to be with the...