I have 6 easter eggers in a styrofoam incubator. Today is day 20 and this morning I noticed 3 have pipped. By afternoon, two chicks are completely hatched. Three eggs are doing nothing and 1 hasn't made any progress at all. I'm afraid the pipped chick is dead, how do I know?
pipped but not hatching
Featured Stories on BackYard Chickens
Eggs can take up to 24 hours from first pip to zip. Every egg hatches different, so I wouldn't worry about the pipped egg at all if the chick pipped on the right end (near the air cell). Sometimes a pipped egg will just sit there for a long time, then suddenly you'll start to see a bigger crack!
Chicken eggs hatch day 21 (if temps have been right). I'd say you're right on time with the other eggs. They may pip tonight, and hatch day 21.