I set 24 BO eggs on Saturday. 12 were from mail order and all of the 12 mailed ones had detached air cells, just rolling around in their shells. I let them rest 48 hrs then went ahead and set them. I'm hoping they will do fine, will just have to see. Time will tell.
Hens go broody when you don’t want them to… and won’t go broody when you do. 
