Two things I would have loved to know before going into labour:
1. Cold feet slow down labour. Get those feet warm or socks on. I gave birth to our twins in winter and I walked around like a mad woman in the snow to help bring on contractions. In the rush the first ones I could find were my summer slippers, the walking helped but definitely not the cold feet.
2. Magnesium also slows down labour. Makes complete sense as it helps control braxton hicks (early contractions). I was so scared that the twins might come early that I took magnesium till 38 weeks. In retrospect it would have been completely fine to stop earlier and my contractions might have started sooner. After my waters broke early in the morning and a lot of time had passed, I had to be induced. Magnesium is great but not till the very end of pregnancy.