First started drinking around age 13. Drank for a year or two and stopped - I think even then I knew I had a problem as I quit cold turkey, although now I couldn't be sure of why.
Started again at age 19 binge drinking and continued until age 28. Clean over a year, then relapsed, and now I'm 30 and this will be the age at which I become sober for good
That being said I didn't realize it was a problem until I was 27 or 28, even with the DUI I got at 23. Apparently that wasn't a sign of any issues for me