How long does it take to become an alcoholic?

I’ve been drinking pretty regularly since did 10 months in prison for a fairly silly crime… it had a big psychological impact on me in the way I had to share a cell with numerous complete strangers, one being a psychopathic murderer who burnt someone alive -in their sleep- (and i had to sleep in the same room), and lived in a very hostile environment for that ammount of time…. my paranoia hasn’t gone away since release a nearly a year ago… I find I can only relax after a few drinks and it’s difficult to leave the house without drinking which I assume is becuase I spent so much time in bed in a cell… I also lost all my drive in prison so I also use the alcohol to dull my emotions… but I’m determined not to be an alcoholic/ dependant… does anyone know how long I can drink for without becoming physically dependent on booze?… I currently feel like i can just quit at any time but its becoming compelling that I buy alcohol during any shop visit…. thanks