Pooping in the nest box?

Hello! I'm brand new to chickens, I just got mine a little over a week ago. I got a variety of breeds (went to the farm and picked out the pretty ones hehe). The farmer told me they were all hatched out last spring and are almost a year old. He told me that they probably wouldn't lay for a few days due to the stress of moving to a new home, but its been over a week and no eggs! My coop is big enough and doesn't have drafts. I put in a foam board of insulation in case they were cold, but they are just pecking holes in it, so I think I'll take it back out. I haven't put in a heat lamp yet because honestly I don't think they need it. (I'm in southern IL and night temps are usually above 5*) My next guess is that I'll need to put in a light to increase hours of daylight to get them laying. I'm having fun with the trial and error.

But my question is should they be pooping in the nest boxes? I've been cleaning out the straw in the boxes every 2-3 days because if they ever do lay an egg it would be pretty gross. I think they might be sleeping in the nest boxes. Would that mean they feel cold? Any ideas? They have roost poles, but they are above my head with a 2x4 slanted along one wall to walk up there. Maybe they can't get up that high and I need to lower the roosts... So much to puzzle out! This is fun!