I would recommend you get them at the same time as chicks, though.
I'm having integration problems with mine. I originally got 3 Easter Eggers and planned on getting other chicks at the same time, but due to them not being available right away, there ended up being a two month gap in ages. Now I can't seem to integrate them without my EEs getting overly violent towards the Orpingtons (even though they are bigger!). They also jump on my silkies and I'm afraid they'll hurt them because even though they are close to full sized, they are so much smaller/lighter than the EEs.
I'm planning on a 2nd silkie coop to keep them safe (plus I think I have two roos and one hen). I'll eventually have to let the Orpingtons fight it out and figure out the pecking order with the EEs but I'm allowing them more time to "beef up"--they are already taller, but just haven't filled out as much as the EEs.