Chick #2 just came out - kind of answers your question actually Ashem...it pipped last night at 8pm, and starting zipping this morning around 9am...its taken four and half hours to zip - I was getting very worried about it - that's a long zip time. Pip to starting to zip is about 4-12 hours on average I think. Zipping is typically around an hour or so. He looks exhausted...
I mostly get concerned when they've pipped for 14+ hours without progress, or when the made the hole bigger over a few hours but you still see the beak showing they aren't rotating.
And yeah, I love buff orpington's because they are docile, gentle and loving. This one is already showing that - every time I come near she throws herself across the other eggs willy nilly to get up to the window to me.
So, current count: 2 chicks, 7 pips!! 4 eggs not doing anything (of which 2 I think were gonnas on day18).