Hi, I think it is normal, very slow process. I had 2 born yesterday afternoon, 2 born last night, one born today! Checked the eggs and noticed that there is one more pipping.
I also had one that started piping, was almost completely out but died in the process...I think, because I can see part of the chick through the cracked eggs, but it does not seem to be breathing or moving. I still have 5 more eggs that so far nothing has happened. I ead somewhere here in the forum that hatching may take a few days.
Good luck with your hatch!