From personal experience, a long time. not days or weeks. I drank a fifth a day for a year straight and didn't notice any signs of dependence / withdrawals when I stopped. Alcohol is a demon, but to become physically addicted to literally a poison takes some serious effort. My mom drank for 30 years as an alcoholic, 10-12 drinks a night from 5 on and never got the DT's or shakes when she quit a year ago.
I am irish, but its not like with heroin or something. Alcohol dependence likely would take daily drinking for over a year in absurd amounts.