Provera & birth control questions ?

I have very irregular periods, and my latest period lasted for 3 months. Went to gyno, had a very unusually thick uterine lining and was prescribed Provera to induce heavier bleeding to start the process of regulating my cycle.

About 2 days after finishing Provera, I did indeed begin bleeding. It's honestly the worst I've ever experienced. The pain is absolutely insane, but I know from years ago, that this is a process to get regulated, so I'm dealing with it.

My question is, I was to start BC right after Provera because the doctor said the heavy bleeding should happen during taking it, but it started after, so is it okay to wait until the bleeding slows down to begin BC, rather than immediately?

If you've experienced this, advice/input is absolutely appreciated!