Quote: Never a dumb question-- only one that is never asked. At lockdown because of the increase in humidity the rate of moisture loss slows or even stops, again deending on the humidity relative to the local ambient humidity. SO may not be worth the effort at that point, before yes, I need to go look at 12 shipped FBCM eggs in my incubator and see if I should sand them also. Sometimes it is hard to see the aircells, I often think they are not developing. My last batch of marans were a very pale egg and grew huge air cells without meddling.
If you have eggs with air cell too small you need to rectify it before lockdown, even delay lockdown if necessary. If you see a pip INCREASE the humidity pronto. Did you find the instuctions?? DO not move aka shake the egg to sand rather move the sand paper in a circle. Make sense?