I think you should get on Propecia now! You are in a good position, you have great hair.One pill a day should help you maintain what you have, or at least dramatically slow further loss. If you tolerate propecia well which most people do, then you can probably look in the mirror 6-10 years from now with similar hair.
You have noticed yourself thats its receding/thinning so start treatment now. DONT WAIT until the symptoms are visible to everyone else because by then its too late you cant get it back.
I got on propecia at around 22 when i first started to notice temple recession. Maintained great hair for 5-6 years, since then (4 more years) its thinned considerably and my hair is now not as good, but this only confirms to me that I made the right decision way back then. If I had not, im convinced I would be bald right now.
Good luck.
edit: Forgot to mention, for you I would not worry about minoxidil. Save that for 5-10 years down the line in case finasteride starts having deminished effect, such as I experienced.