Hens only lay an egg a day.So take into consideration how many egg's she has if she layed them all herself.If you set the egg's under her from different hen's around same time they "should" hatch within a few days of each other.I generaly leave egg's in nest at least a week sometime's.Most of all the hen's I have ever had let me candle the egg's.But in major brooding sometime's was just too many to mess with and lef them do thing's naturaly.Most of the time good broody hen's will roll out non hatcher's or dud egg's.Some will break and Phew if you leave them too long.Hope you get lot's of babie's.My neighbor's White Rock has a clutch of about 8 mixed babie's a few week's old and they have been foraging down there they are so cute.Love the mama hen's with babie's.