If you have MPB I would get on a regime of propecia, nizoral shampoo, and possible rogiane immediatly

deca is supposed to be pretty mild on the hairline, if you are predisposed to balding then you might encounter it no matter what.

Nizoral - leave in "conditioner/shampoo" or w/e (prevents DHT from forming on the head)
Rogaine ExStr - Promotes gains -----topical liquid
Finasteride - stops DHT from forming on the head. Pill -take 1mg daily. (argueably 1mg)