I don't know if it was just coincidence, but after a 1st birthday party we'd been to, we stopped on the way home to order takeaway...I ordered a hot Tom Yum. THEN, because the wait was going to be long, we walked all the way down the main street and back. Got home, ate said hot Tom Yum, got ready for bed. DP decided that it was time to DTD. So we did. Not more than a few hours later (in fact, would have to have been about 2 hours later), faint cramping sensations woke me up. And they only got more and more regular...about 36 hours later we had an Oscar!
So, for me, the long walks, hot food and sex worked. But our birth centre due date was the day we did the walk and everything else, another due date was the day before that and the day he was born was the first scan's due date...so it might have been about to happen anyway, without our pre-empting it! And I wasn't in a hurry to have him out, so maybe that's why - when you want it over, they hang around in your belly, isn't that the rule??