37weeks with 3rd baby head fully engaged, how long till labour?

im 37 weeks pregnant and saw my midwife 3 days ago and she said that baby's head is fully engaged, i told her that the pressure from baby's head is very painful and that the tightenings are very Intense! she said it could mean that baby is ready to come out soon and that i should get my bag packed coz she thinks i wont make it to my due date(22july), i know that with your first baby the head can be engaged for weeks before labour but its different with 2nd 3rd ect.... this is my 3rd baby,i would like to hear of anyone else with 2nd 3rd baby ect... of how long after been told baby was engaged they went into labour?