How many days does it take for geese eggs to hatch from the first day the goose starts laying on them?

My geese seem to take btween 3/12 to 4 weeks...BUT they may lay eggs for several days b4 actually sitting them . I have several geese and several future moms will lay in one nest then they take turns sitting she ( they.... must not be disturbed) and the geese and nest are particularly vulnerable during this time! ( keep safe from dogs and other critters ) Be sure to start counting days from the actual day hen "goes broody" she will not leave the nest and she gets a hunkered down expression on her "face" I keep water in a shallow dish near by as the newly hatched goslings will need it... shallow so they don't accidentally drown.