Hi Juwi - your post got missed. When you're peri-menopausal then your natural cycle by definition will vary from month to month although may go through more regular times . Since HRT generally does not suppress the cycle ( certainly not 50 mcg patch anyway) then your period may well come at the "wrong" time. Depending on how long you've been on HRT, if your periods were regular then you were not peri-menopausal by the strict medical definition (which goes on cycle length combined with age and symptoms + sometimes FSH tests depending on circumstances).
It is always advisable to finish the course of utrogestan to help prevent excessive build up of the womb lining although if you are ovulating naturally then you will be producing your own progesterone. You won't know this though.
If after a few months your bleed is consistently coming before you finish the progesterone course then you can tweak your HRT and when you take the progesterone - but this may only be temporary while you are still peri and your cycle is unpredictable.
When you are post-menopausal then the bleeding normally starts at the end of the prog phase or just after starting back on oestrogen only. Sometimes eary bleeding indicates that the prog dose is insufficient but in early peri as I imagine you are - this is unlikely I would have thought?
As always if you are worried eg that the bleeding is abnormal, excessive or painful then consult your doctor.
Hope this helps
Hurdity x