My DH was informed by a work mate

yesterday that sex will bring on Labour. Now i did know this and had known it for some time but i had "forgotten"

to mention it to him, for obvious reasons.
Now as soon as his work mate told me this he rang me straight up and informed me that as soon as he came home from work he was going to have sex.
I have had cramps and a sore fufu since last night.
Ok, now that i have informed you of the situation i need to ask -
How much sex do you have to have to get things started? and Maybe TMI but i want this baby out of me, What position is best?