I have some chicken eggs in my incubator and they are suppose to hatch today the ( 21st ), I dont have any babies and was wondering is usually on the day they hatch? or are they late? just worried. also I was told to pull the red plastic plug on the incubator when they start to hatch? also was told they dont need water in there when they hatch, so do i change the temperature when they hatch or leave it between 90 and 100F? thanks so much.