I set and hatched some earlier in the year. My plan is to do some more sometime in late May or early June so that I can avoid having the heat lamps running so much. I'd like the flock to get to spend some time foraging out in the grass as well to get better nutrition going for the sake of more robust embryos. It's been cold and damp so long this winter and I know how much the chickens enjoy the fresh spring flush of bugs, weeds, and grass.