Last year was the first time I tried this. When, after 3 days, 3 eggs were remaining, I actually cut a slit in the tops of the eggs to check. I even went as far as to pull one of the aready-sliced-shell youngsters out of the egg. Of the ones I checked, they all were actually ready to emerge, and within 12 hours all were out wandering. All turned out fine. I don't recommend this, though, as all of the mentioned ones were terrible to get started feeding. Go figure!