I live in WV, so a little warmer here, Zone 6. You will need to keep them inside until they feather out. That varies depending on the breed, but usually 6-8 weeks. Then you can put them outside.
I mention this because that is your guide. Think 6 weeks before its warm enough to put them outside. In your area I would think they could be outside by late April, early May. So count back - 6 weeks for feathering, 3 weeks for hatching. By my calculations you can start hatching in early March.
You can hatch earlier if you're willing to keep them inside longer. I just hatched 5, I've learned that's about all I can handle in the house for any length of time.