i would say you will know when you are in established labour, but everyone is different and so is everyones pain threshold, but majority of women know when its the real deal. I must admit i have gone in with baby bouncing on my bladder i thought my waters were leaking, they said i'm not the 1st and wont be the last that was with my 4th, they even said alot of women go in with constapation and trapped wind. so again no panic, i actually rang ambulance with my 3rd wasn't sure but as my waters had been gone since 22 weeks and i was 33 weeks then thought i best be safe than sorry, well i was in labour and had sat on his head for the 20 min ambulance journey. so even though i am on my 6th and you would think i am an expert I am not and i still panic that i wont know. so you are not alone