One egg out of my last batch hatched 4 days early. He was lonely for a couple days but he's fine. You may just have yourself an "early bird". If he does hatch and is alone for a couple days, a small stuffed animal and a small mirror will help keep him company until his brood mates arrive. Take a deep breath and let it happen.
Increase humidity to about 75%. If the membrane looks dry, wrap the egg loosely in warm wet paper towels. Try to limit the amount of times you check on it so as not to disturb the overall humidity for the other eggs. Keep us posted!
A pip looks like a tiny outward crack in the egg. The small crack usually has 3 or 4 little cracks radiating from a center point. I know there are pictures around here somewhere. BRB with a pic. Also, you can hold the egg to your ear and listen for pecking or peeping.