Don't know what day eggs are on- when to stop turning?

[Goose and Fig]

I am going to be putting some eggs that were left by a second hen under a broody mom. The first set of eggs are due to hatch in about a week. I want to take whatever eggs are left and incubate them. How do I know when to stop turning if I don't know their "due date"? If/when they start peeping or pipping? Also- changing the humidity? Thanks!

 

[BeautifulBlue]

If you can candle them that would help you a lot. You can tell how far along they are by comparing pictures online (theres quite a few links to candling pictures on BYC) If you cant candle them, I guess if it was me, Id just keep checking them for pips then stop turning and bump the humidity

 

[Goose and Fig]

Thanks- I never thought to do that! Kind of like an ultrasound for eggs. It's only a few eggs- but the other last chicks we got- RIR x Buff Orpington- are gorgeous. I'd love to get a few more.