Right away, or they will hang combs from the cover.
I put out a nuc to trap a swarm last Thursday. At the time I only had 3 drawn frames so they went in. I built some others this weekend and went out this evening (Wednesday) to put them in and the bees have already moved in. I don't want to scare them off by messing with them to much. So do I let them settle in for a while or do I pop in the new frames right away?