Depends on the specific clutch, but we never cut before day 50, or before the eggs seperate from each other easily (if in a clutch where they were touching, of course). If they do not easily come apart from each other, we do not cut. Some we cut on day 50, most at day 52, and they're crawling out a couple days later. . If they're still cemented together, or if they are still very plump with no signs of dimpling, we will wait longer.