Don't open the incubator. =) Chicks can take anywhere from 30 minutes to 24 hours to actually hatch out of their shells completely. My friend's best hen laid an egg that took 33 hours to hatch out, and it ended up being a very healthy chick! Some won't hatch because they're not strong enough. Others won't hatch because there are developmental issues or deformities, and it is best to let them pass away if they don't pop out by themselves. I didn't agree with this at ALL when I first started researching chickens and I thought it was inhumane and cruel to let a chick die in the egg when it's obvious it's alive after it pipped - but it really is the best thing to do for the chick.
That being said, your chick has plenty of time left before I'd start to worry. =) I wish you luck, and praying that your chick(s) hatch successfully and are nice and healthy.