I think, generally speaking, that is the expected pattern.
And I fit it!
My first labour birth was 5hours 15mins from start to finish, my second 1hour 40mins.
My third wasn't until over 12 years later and again was around 1hour 40 mins.
You're just going to have to get yourself to the hospital quick-smart as soon as you think things are starting! Even if that means a couple of false starts...after all, you wouldn't want DC1 acting as midwife, would you? 