None, seriously!
With my twins I was induced with Cervidil, and labor started about 4 hours after the induction. Just got crampy and suddenly they started to HURT. I was like, "Hey, this isn't supposed to PUT ME INTO LABOR, is it?!?"

With #3, nothing, nada, zip. I was waiting for after my sil's wedding -- she had her wedding 4 days before my EDD and instructed me to PLEASE NOT RUIN *HER* SPECIAL DAY -- and I remember the day after her wedding I woke up and was like, "okay baby. Time to come out" and NOTHING.
On my edd, I went out with my twins to the park and chased them around for a few hours, then we all came home and took a big nap. Sometime during my nap, my water broke, and I didn't even feel it or wake up! Still nothing for about 8 hours, til I finally got on the breast pump.