First timer moving pullets to the coop in the summer heat.

I would definitely put them out now, assuming you don't still have a heat lamp on them. They will be much happier, and less likely to develop any bad habits. You could put them out at sunset in the coop so they spend their first night in there, then see if they go in the next night on their own. I would hate to shut them up in the coop, too, for more than overnight.

 

I think the whole "confine them to the coop" thing is more for free ranging. Using a coop with an attached run, I've never confined birds only to the coop. Sometimes it takes littles a while to figure out where to go to sleep, but with my set up it's okay to sleep outside also. If you want/need your birds to sleep in the coop, you may have to put them inside at night for a few nights, but that's okay.

 

Try moving them out there at night, and just locking them in all night. My girls free range, but I never locked them in, I just called them the first couple nights and fed them then.