The normal incubation period for chicken eggs is 21 days--hatching at 18 or 19 days is too soon, and usually indicates too high of a temperature in the incubator or some other issue. Chicks that hatch too early or too late invariably have health problems or tend to do poorly.rom reading somewhere on the internet I think it said that it can take up to 40 hours from pip to full hatch out of the egg. that is close to 48 hours or two full days. It also said to NOT OPEN the incubator during this period.