Sorry to say this is my experience....
Sunday 17th June.... irregular contractions
Tuesday 26th June.... stretch and sweep, I was 2cm and stretched to 3cm
Friday 29th June - very very bad contractions, still irregular, 3cm and stretched to 4cm
Saturday 30th June... 9.50am 5cm, waters were broken by midwife at 7pm, baby born at 9.50pm!