can't predict weather.. every region is a bit different. i live in michigan and planting outside before May is risky. we've had several frosty nights at end of this april alone. think you are bit furhter north than i am? latitdue? but probably very similar context nonetheless. Early may is looking shitty... i'd wait.
in the meantime, yoe may want to expose them to increasing hours of sunlight each day. See any light damage or major wilting, it's too much for them and they'll need to be hardened off to it.
historical reference.. other ppl in area will be much better at giving a specific date.