I would echo the above. I can't say for sure how many days they all took because some of them were taken from a nest after a coyote took the hen right off the nest.
I would say most of mine hatched right out at 28 days though. One thing I would add is that you need to be careful with the humidity and resist the temptation to open the incubator during hatching. I had a few problems with the keets being able to get out of the shell after I opened the incubator to pull several out. The membrane was sticking to them and they couldn't get out of the shell.
The shell of guinea eggs is much tougher.
Btw, if you happen to be in WA, I'm running a sale on keets right now. Buy five and get one free!
God Bless,