I normally lately listen for tapping. Around hatch date, a fan might cover the noise but I am hatching in 2 LG still airs, so no issue for me. I found with mine I can notice this better than waiting for a roll or a chirp. I can generally hear it before seeing pips (Though they are shortly coming once you hear the tapping) and not all eggs roll before pipping.
Last I checked I was at 10 chicks and ALOT of pips and a couple zippers in hatcher. BYM and I hope pure BA. 9 blacks and a white chick so far. But that was 2 hours ago. 28 or so left to finish up. I pulled 2 clears when I moved to hatcher from cooler bator. Had to make room in brooder for tomorrows move into the world. Since my ducks finished fluffing up today I left the bator going and am moving chicks to the empty one after they hatch. Bator was pretty full and these chicks are extra active when they hatch for some reason, had 1 BA jump a welded wire partion I had in it 2 in. tall) So I breaking rules but its working for me. Don't ask me how I rolled these guys...
Probably gonna regret this because I have 62-ish special bred eggs in cooler I am doing EVERYTHING the "right way" and will probably end with like a 3% hatch. Such is my luck. Good hatching all.