I was certain DS1 would be a week early (he was ten days late), and I "knew" that DS2 would be late, but I went into labour bang on my due date.

With the twins my prediction was that I would go into labour about 2am, and I did, but the date I cannot pretend was a surprise as I had given myself several sweeps and was aware I was 3cm dilated when I went to bed the night I went into labour