hey miss muffet: it's going to take what it's going to take. Yes, it will be helpful for him to start experiencing tough consequences from the get-go. Those are always helpful in the long run. But having been where you're at (my AS is now 24), i know that those consequences are just a blip on their radar screen because young males in this country are young punks - even the ones who do not engage in partying-type behavior are young punks who think they have total control over everything in their lives. From my observations, it's not until the mid to late 20s that our loved ones start wearing down and become willing to make a major change in their life - and that's even with a family who does not enable.
So keep doing what you are doing and dig in for the long haul. Keep coming back here for ESH and to offer us yours!