When to place in incubator?

[Tricia G]

I am receiving chicken eggs today to start hatching with my class. I have read different sites and know to place in the incubator at different times throughout the day, but there is some inconsistencies with how long to let them sit in their shipment box PRIOR to placing in the incubator. Please advise!
Thanks

 

[Dr Evy]

I always let eggs rest for 24 hours after shipping to let the air cell settle.