You *can* make a safety hole at 18-24 hours after internal pip, but if they're chirping away, you can leave them a little longer. The danger is at about 30 hours after internal pip, by which time they can start to run out of air.Thanksmostly wondering when I need to consider a safety hole. I really didn’t want to have to help…
Here's the Assisted hatching article just so you can have a little read up, but keep in mind that ducks are slower hatchers, and can take days