at the hospital here you preregister at 32 wks, So as long as you have done that registration then they tell you when your water breaks or when the contractions are 5-7 mins apart.
They say 5 minutes but I would go in at every 10 minutes + you want to pre-register at hospital to get in a bit quicker. I hated when I was 5 minutes apart with contractions and they were mone concerned with my birthdate. Haha uhm . I remember saying i didn't have one and unless you me to hit you in the head you might want to ask me later then my water broke haha left them a nice mess. Anyway
About 5 minutes apart lastings about a min long give or take.