SKYRIDER, you need to just put enough eggs that the hen can cover them all. Usually about 10 to a dozen. If she can't cover them all, usually you get a very poor hatch, because the hen turns the eggs several times a day with her beak, so the ones under her get rolled out where they cool off, and the ones out from under her get rolled back under, so that all are ruined. If they have started to grow a chick, then get rooted out from under her and get cold, that kills the embreo, then the others under her get rooted out into the cold at different times, and also die.
About a dozen is a small enough amount that she can keep them all warm.
Just save eggs till you have about a dozen, then put them under a hen that is sitting. If you don't have a sitter, don't bother saving fertile eggs till you get one, as you never know when one will decide she is ready to hatch some babies.
Good Luck. Oh, also, you need to keep a setting hen on eggs seperate from the rest of your chickens, as if she is in with them, they will crowd into the nest and lay fresh eggs in with the ones she is trying to hatch, and again there will be too many eggs under her.
