Here is an article with lots of good information:I have about 9 eggs left in the incubator that have all pipped. I lost one already during hatching. How long before I help them? They have been with the same hole for over 8 hrs, and it looks like it is breating heavily. I don't want to lose anymore. Any ideas?
https://www.backyardchickens.com/articles/guide-to-assisted-hatching-for-all-poultry.72886/