I've done over 20 hatches now, both in my incubator and under broodies, and over 3/4 off my hatches like to start pipping on day 18, if they're not fully hatched on day 18. This is currently happening as we speak, actually... So, I've posted about the phenomenon before and had others share similar experiences. It's safe to day 21 days is a guideline with wiggle room. I can assume my hatches will probably be early. Would there be detriment to the chicks if I stopped turning on day 16 and started lockdown then? Even if they do, by some odd chance, wait until day 21?