How does "true" labor actually start?

MommyNApril

I'm concerned I am not going to know I'm in labor and get to the hospital too late for pain relief. I've endured some pain from fibroids. I don't want to dismiss the pain as just another bad cramp. I guess the best way for me is to not ignore any possible signs. Knowing everyone is different (including the hospitals, I'm learning) What are some of your experiences?