I read that after a chick pips and his beak is out that it can be 12 hours or so before it hatches. But, how long can it go before it breaks through? I came home to 1 hatched chick & 2 eggs that have a crack. Not a hole yet. Since I wasn't home to see exactly when that appeared, I'm not sure how long its been. But I know for sure 3 1/2 hours. I'm envisioning 2 chicks stuck in their eggs with no air.