Out of all five of my babies, my waters only broke once spontaneously without me actually being in active labour. And that was number four son.

DS1 I was induced and they were broken for me
DS2 They were broken during an internal in labour
DS3 broke while contracting
DS4 spontaneously at home while sleeping (made a big mess too ) labour started about 2 hours later
DD was induced again, with gel this time but waters broke with contractions about 2 hours before she was born

Good luck I hope like me you dont have a set pattern to your labours and that you get to have your VBAC