When hatching your own eggs. Keep a bowl on the counter, date the eggs with a pencil as you gather them. Then use the old ones, keeping the fresh ones just in case. Every couple of days, anything more than 2-3 days, I put in the fridge.
Pray to the broody Gods! Hope you have a good broody breeds. Put a pile of golf balls in the nest, and pray some more.
If you get a bird that looks flat, with a trance like to her eyes, and then as you approach growls and blows up like a beach ball... WAIT 3 day!!!!! Vitally important is to WAIT the 3 days. Because what has happened to me more than once, twice or three times, cause it is so hard to wait, is I set a clutch of eggs... and she is not sure... and gets off, then two days later gets real serious, and I don't have any more eggs to set!
Good luck, I am currently in the piling up of eggs and praying hard stage.
Mrs K