I recently bought 2 nucs, one was stronger than the other and 3 weeks after getting it I noticed about 8 swarm cells, I destroyed them and within a week they were making more.
So I split the box taking all swarm cells and leaving the queen with everything else.
the swarm cells are due to hatch any day now and the queen right hive started to build more swarm cells, I took one frame with 3 large cells and made a small nuc with a really full frame of sealed brood and a frame off uncapped honey from another hive.
So I now have two colonies waiting on swarm cell queens to hatch, one in the original box and the second small nuc made up of only 3 frames.
I feel the bees knew we were going to get a bit of rain and started to prepare for a swarm, within days we had 60mm of rain.
We currently have a pretty good nectar flow happening here, tons of pollen coming in as well.