Introducing chicks into an existing flock.

I started out with 2 chickens who are now 6 month old and one of em i swear is gonna start laying. soo exciting.
Anyway i was wondering how long should it take for the hens i introduced to the existing 2 chickens to establish pecking order? i had them separated for 3-4 days and i separated them obviously starting pecking right away and there has been no blood or violent clawing or any of that just a lot of dominant pecks. its calmed down but how long should it take until they all get along? it probobly isnt ideal to have a 3 month difference but i had to put them in the coop soon cuz they were getting really big. any help? (Sorry if i wasnt clear in detail any questions i can ask you in the discussion)