My first 3 labours just happened...contractions 5 minutes apart then babies 4 to 6 hours later!! No loss of mucus plug, no water breaking...just straight into it, LOL.
My 4th baby I had a 16 hour pre-labour...slight loss of mucus plug, painful but sporadic contractions...again no water breaking. (the midwife had to break my waters all 4 labours...and babies came soon after). With my 4th they did a stretch and sweep when I got to the hospital and I had Jack 4 hours later.