I just hatched seven chicks. I didn't see any of them until day 23 or 24. I had mine under a broody hen though so I couldn't see what was happening until I looked under her. That's them in my profile pic with Mama Hen (as of May 2017, it may be changed in the future.)
If they are this late, you need to check temps, check the thermometer for accuracy. Forced air should be 99.5F and still air should be 101-102F. Late hatchers signify low average temps during incubation.