and Welcome To BYC! X3 It is best to wait until the pullets are at least at pol, before that they should be slowly introduced to each other, through wire seem to work best, ie dividing the coop into two sections or keeping the new/younger ones in a cage inside the coup for a couple of weeks to a month at least. They will get to know each other and sort of work out a pecking order before actually coming in contact with each other. Adding a rooster to a flock usually goes a lot faster than adding more hens, but it still may take awhile. There is a nice article in the Learning Center on integrating flocks you might like to check out, the part about actually combining them is after the quarantine section https://www.backyardchickens.com/a/adding-to-your-flock
