How long is too long once chicks start to hatch?

[Dona Worry]

I have my first-ever batch if eggs in the incubator, 18 polish crested eggs. They are starting to hatch a day early, and I am concerned-- I took this photo approximately 6 hours ago, there are at least 5 eggs at this stage of hatching, I can hear chicks peeping, but they don't seem to be making any headway. What do I do??
Incubator is at 69% humidity, and 99.5 degrees

 

[Crazy Duck Lover]

They’re okay!! They’re in the second stage of hatching known as the “pip”. It can take up to 24-48 hours for them to make anymore progress. After they pip, they zip. The “zip” is when they begin cracking a ring around the egg. The amount of time in this phase varies, but don’t let it go on longer than a few hours if they’re not making progress. Keep me updated! IMG credit: Pinterest

 

[Dona Worry]

They’re okay!! They’re in the second stage of hatching known as the “pip”. It can take up to 24-48 hours for them to make anymore progress. After they pip, they zip. The “zip” is when they begin cracking a ring around the egg. The amount of time in this phase varies, but don’t let it go on longer than a few hours if they’re not making progress. Keep me updated! IMG credit: Pinterest View attachment 3114904

Thanks, I'm so anxious!! I've always let broody hens hatch eggs, and they have always been fluffy and angry for 3 weeks then POOF, like magic, fluffy baby chicks.
This is so much more nerve-wracking!

 

[Dona Worry]

O we have a zipper!

 

[Dona Worry]

Aaaaaand a BABY

 

[Crazy Duck Lover]

Congratulations!!

 

[Dona Worry]

We are up to 8! Hooray!!! I took the first 5 out of the incubator so the rest would have more room. They are all healthy and active!