Marans Eggs candling question

[ChickFila]

I have 14 marans eggs in the bator, and today is 8th day.
When is the best time to do candling for Marans eggs?
I tried 3 days ago and couldn't see anything but air sac through very dark shell.
Any advise?
Thanks!

 

[Magnum_D]

I would look at the egg on the 10th day. Around the 10th day is when the beak hardens, so look for a beak.
-Magnum