Earliest Sign Eggs Are Developing?

[JekkaLynn]

The other day I found one of my tiny bantam hens brooding on a nest she and the other birds like to sleep on at night. She got up for a minute and I found over a dozen eggs hidden deep down in the straw!
I have no idea if any of the eggs are good since the birds sometimes slept on them at night and I don't know if that would have started them hatching then killed them when they got up in the morning.
It had been only a day or two that the hen has been on the neat both day and night.
What is the best way for me to check if the eggs are still good?

 

[JekkaLynn]

Ooops I just realized I posted this in the wrong place.

 

[brunettedixie]

Candle them!

 

[JekkaLynn]

Candle them!

All of them I checked are developing and she had 18 under her! My wonderful husband bought me an incubator and I took all except one tiny little egg from her and gave her some dirty weird shelled eggs to keep her broody. Once the eggs in the incubator hatch I will give the babies to her.