Mine woke me up at 3am.. tight, very obvious pain that I'd describe as a cross between a cramp and a dull ache in both my lower back and lower belly. I started timing and they were coming every 15 minutes and lasting about 30 seconds. It was totally different to what I had previously felt with Braxton Hicks.. I knew it was the real deal because the pains were so consistent.
I kept timing until around 8am, woke hubby, showered and was checked in to the hospital at 11am. My labour seemed slow to progress, I can't remember how long it took to really amp up but I gave birth at 2:47am the next day; so, from the time I started feeling the first contractions to the time i actually had him, it was almost exactly 24 hours, but my hospital records state that the official "true" labour only lasted for 7 hours.
Hope this helps