Chicks will rest for long periods inside the egg. A pip on day 19 is not unusual, but it also does not mean the chick is ready to hatch. They can take 24 hours or more to fully emerge from the egg. They take their time and come out when they're ready (typically after they've fully absorbed...
Here's another very informative thread that many new members may find helpful.
https://www.backyardchickens.com/forum/viewtopic.php?id=45583&p=1
These are all linked in the "read me's on hatching" sticky at the top of this forum. There are also many other great links to help with...