Don't, the shells will not hurt them. This is your incubator and you can open if you want. I never open mine till day 22 as you probably have read and the reason is in the beginning as soon as I opened the first time to remove the first hatch---I started having problems with the others hatching slower, not hatching, dying after pip, dying before the pip. Once I just left them alone---hands--off, not opening for NO REASON, my hatch rate went way up. Now I either get 100% or almost 100% on Every hatch(eggs at lock down). It might NOT hurt you to open yours all you want---I do not know----I just know it does in my area. Having all the shells in there and the chicks rolling the eggs like bowling has NEVER affected my hatch. Good Luck!
A pic of chicks just being taken out on day 22 in just 1 of 4 trays. The tray cover was removed before the pic was taken. 2 eggs out of 164 did not hatch----almost 99% hatch rate on this hatch. The only way I would open the incubator before day 22 is if ALL the eggs hatched before then.
Edited by PD-Riverman - 3/5/16 at 8:13am