Just turned 20 with hair like im 40??

[Chief Ohio]

Well first off i noticed my hairline was receding about a year ago but chose to wait it out instead of jumping on propecia. The feels of realizing i was losing my hair so you g hit hard and my first semester of college was rougher than expected. I did go see multiple derms who all gave me scripts for fin, I was terrified after reading stories all over the internet about guys who could never get an erection again or had permanent hormone problems.
So now a year later I'm about to turn 20 and my hairline had turned to shit i can no longer cover my temples and I'm willing to give propecia a shot!
I would start with 0.5 mg's a day. But i have a few questions..

Am i too young to start propecia?
What are my chances of developing permanent side effects?
How bad is my hairline now? and how much is it possible to save?
It it too late to save and i should just shave? At 20!?
My PICS:
http://i.imgur.com/xujyVkh.jpg
http://i.imgur.com/jpkdueA.jpg
http://i.imgur.com/Mr4gixE.jpg
http://i.imgur.com/2X7IIZK.jpg