I did! It totally caught me off guard. I went from contractions every 6 minutes to every 2 minutes in just an hour or so. It was three days before my RCS. I went in at midnight and they made me wait until 8 am since it wasn't an emergency. They stopped labor, gave me some drugs, and I was supposed to sleep until it was time for surgery.
I don't see any reason to wait if you are in active labor. Like I said, I only had to wait since it was the middle of the night.