I always struggle with this one thing - I put my eggs in the incubator at the same time, and of course they begin hatching pretty close to the 21st day (sometimes slightly early, sometimes right on time and others who straggle a bit behind). I've been told not to open the incubator until all the eggs hatch. How long can you leave a hatched chick in the incubator waiting on the others? Should I open it long enough to snatch the hatched chicks out at some point?
