Most people will tell you 7 to 10 days, but stop and think how long it may take a broody hen to lay a clutch. At one time I had one metal Sears incubator. I would hatch a batch of eggs, disinfect, and start another batch. Many of those eggs had been held in excess of two weeks. I generally managed high percentage hatches. Incubator was maintained and eggs were stored in an earthen cellar where the temperature was around 65 degrees F and humidity 50 % plus and minus. Eggs were stored in clean trays of bedding and turned daily. Worked for me.