https://www.backyardchickens.com/articles/step-by-step-guide-to-assisted-hatching.64660/
Here's a big long article on assisted hatching. It says that eggs pipping, then appearing to do nothing for 18-24 hours, is normal and nothing to worry about. The chick pips and then absorbs the yolk sac...
When you candle the eggs, you can check the size of the air cell.
That can tell whether the humidity has been about right all along, or too high or low.
(It's a way to double check what has been happening, and learn for the future.)
Here's an older thread with a sketch of how large the air cell...