What Causes Heavy Bleeding During Menopause?

I am 53yrs old and started the menopause with heavy bleeding and less time between periods. I have been prescribed MICRONOR to try and allev iate bleeding. I have no other symptoms. I do not require to use it for contraceptive purposes. However, the instructions state that it should be started on the first day of bleeding. I am just finishing a period and dont want to wait until starting my next priod before starting this treatment. Can I just start taking now?