hatching time?

[Flo]

Hello,

I've been incubating a friend's ball python eggs. Although the eggs were fairly dimpled (they were given to me after at least two days spent on the substrate on the warm side), they started to hatch a couple of days ago. Out of 9 eggs, 4 have hatched (2 babies are out, 2 are poking their heads out).

How long will it take for the whole clutch to hatch? (So far, I had only hatched corn snake and pituophis eggs.) I'm wondering if the "slowness" is normal for BP eggs, or if some of them have died in the egg from being too dry and dimpled.

Thank you.