Hello and welcome!
Finasteride is a DHT blocker and may or may not counteract Testosterone and cause feminization. If you are taking it for your hair (common case) then it's ok. But if you are taking it to help PM feminize your body then there are better substances (white Peony, apparently, above all).
500 mg of PM is a very small dose that is unlikely to cause any effect. The advised dose for women in menopause is 1000mg/day and I would suggest to take at least that much if you want to see any effect.
How quickly you'll get an A cup depends on a multitude of factors, from diet to pure luck, but mostly it depends on your body shape. It takes way more tissue to build an A cup on a chubby chest (like me, band 38) than on a slim body. Anyway, even with 1000mg/day and a medium/thin frame it is unlikely that you'll see any permanent growth in less than 3 or 4 months, and you are probably 6 to 7 months of continuous use away from an A cup.