I have done both - let them sit and not let them sit for at least 24 hours. In my opinion letting them sit did help. I got one shipment that was packed great, but post office had most of the air cells loose, and a few were detached. I only lost 3 out of 27 eggs - 2 did not develop at all, and 1 quit around day 6. We'll see how they do at lock down and hatch. But, I'd say that letting them rest definitely increased my chances of a good hatch since most of the air cells reattached. I will say that with loose or detached air cells they certainly seem to lose moisture more quickly. I am compensating for that with increased humidity in the incubator since I noticed it around day 10. Have my fingers crossed!