How Long Does Provera Take To Show Effect?

I had been on Primulot to control bleeding and it worked with 2 or 3 tablets daily, I only had minimal staining. After a referral to a new Gyny I had a D&C to evaluate whether or not I was suitable for ablation or needed a hysterectomy. I m premenopausal and still fertile. Ablation was not an option and since the D&C my bleeding is slowing increasing and is red like a normal period. I have been prescribe Provera and it does not seem to be working at all, I have been taking 2 tablets daily for 3 days and the bleeding is increasing. Does it take time for Provera to work or should I return to Primulot, wish is more effective for me?