Sometimes you can see the eggs rocking as the chick moves around inside the shell getting into a good position for hatching. After it is in position and it rests a bit, the chick will peck a hole through the egg shell so it can breath. This is called pipping. Then it will rest, sometimes for a very long time. Then it will zip, which means it cuts the shell in half so it can push the egg shell apart and come out. Then it rests, usually not for a very long time. Then it pushes the egg shell apart and a very wet chick pops out. It lays there, rests, and dries off a bit. Then it gets up and plays soccer with all the eggs that have not yet hatched. Eventually all that are going to hatch complete the hatching process. Don't worry about the eggs used as soccer balls. It does not seem to bother them.
If the average incubation temperature is a little high, they should hatch early. If it is low, they will hatch late. Some areas of the incubator can be different temperatures, even with a forced air incubator. In any incubator some will hatch earlier than others. It is not a big deal.
Hope this helps.
