Thanks guys. I set them all on the same day from hatching eggs I ordered in the mail. That is why I was a little surprised that the hatching seems to be spanned out over a longer period of time.
I have a hen that is sitting on 13 eggs. Today is day 21. Two hatched yesterday, and two today, although one of those appears to have been smothered to death. One more egg has pipped today. How long do you hold out for the others?