It's hard to say really, I think it can vary a lot from person to person and what kind of state your head is in at the time. I mean you can become mentally dependant very easily I would say but if you mean physically then it's probably going to take a lot longer.
I was a really heavy drinking for 3-4 days of the week for a good 7 or 8 month. I'd drink easily 10 pints of beer/lager plus a lot jager bombs/shots/vodka and cokes on the days I'd be drinking and I never came across any physical dependency luckily. However I was somewhat mentally dependant, I'd want to always go to the pub with the lads whenever I wasn't already at the pub drinking. I mean, they'd make other plans what didn't involve drinking and it'd just make me sad since I'd rather be having a drink in the pub because it was much more fun.