Great news! I've not hatched in a bator before, but I'm sure others will advise on how long you should wait.
Its Day 21 for us and 2 of mine under the bantam hatched last night too. The third egg is pipped. not much happening to the 4th. Mama Mille Fleur is holding tight thank goodness.
Baby chicks don't need food or water for up to 3 days. And if one is early, most likely all will be early. It will be just fine in there until the rest hatch.
Thanks all for the advise. I was just so suprised, I wasn't expecting anything until Monday. I have another that has hatched so I feel better now that she has a buddy. Hopefully I will get pics up soon.