The time of day you put in the eggs generally doesn't make any difference as to when they hatch. Different chicks will hatch at different times. I've found that a few of our chicks hatch a day early, despite the temperature being exactly what it should be.
Did you start your day count the day you put the eggs in or 24 hours later? Still or forced air incubator, what temp through incubation, what humidity? The time of day makes no difference really, some will hatch early due to lower temp, some will hatch late due to higher temp, some will obligingly hatch right on time. What breeds are you hatching?