This is pretty normal. There are a lot of different reasons chicks can hatch early or late. That’s why some hatches can stretch out over a couple of days. Humidity, heredity, how and how long you store the eggs before you start them and just differences in individual eggs. Most of my hatches are over within less than 24 hours of the first one to come out, but in my last hatch on was out and walking around a full 24 hours before any other egg pipped.
The big reason for most of them to hatch really early or late is the average incubating temperature. If your incubator is running a bit warm they can hatch quite a bit early. I’ve had eggs pipping when I went into lockdown because of that. If your average incubating temperature is a bit low, they can be quite late.
21 full days after you set them is the optimum time, but even of you get it perfect, some will be early and/or some will be late.
You might want to tweak your incubation temperature just a bit to lower it, maybe a half degree, before your next hatch.
Congratulations on this hatch. Sounds like it is going well.
