We are into your May now (next month here is the start of summer - we go with the start of December for summer). Yes, I have split them (that was in the second week of September) and have three newly mated queens out of it (all lovely looking insects) heading three new colonies-all laying beautifully, and kept the older queen in a nuc for further use -as needed. I took a bunch of capped brood from the original colony too -to boost another colony. It was a big one and very happy to keep drones going all year. Masses of worker brood too though. I reckon it would have swarmed in the last week of September.