I think that your background checks are already done. There is no sense in VO for sending MR if you don't pass security checks. Sometimes they ask for new police certificates at the time of MR but they start the initial checks once they finish the eligibility assessment review.
I got MR first (second line on ECAS appeared the day after) and once all of us finished medicals (we didn't go together since we live in different countries), 3 weeks after that I got RPRF request. Medicals received status showed up 13 days after they were completely done.
Since we don't have to send passports, Decision made status appeared almost 2.5 months later (followed by the short email from VO) and COPR letters arrived after that. There are no rules. Every application and every applicant is specific and no time line will match with the other.
Good luck