Hmm, looks like I'm the youngest one so far at 27.
Other than some comics given to me at Christmas when I was really young, I didn't buy my own until I was 9, and then started seriously collecting at 10. That was also the year I became interested in the Golden Age through a handful of Superman reprints. I also became obcessed with the next "oldest comic in my collection." The older the better. Over the next few years I managed to pick up a later issue of Heroic Comics and Atlas' Men in Action, and later on some issues of Classics Illustrated, and Captain Marvel Jr. #110. Then, when I was 16, we got the internet and I discovered online auctions. I bought a Fox Blue Beetle and another Captain Marvel Jr., but I still didn't know much about the Golden Age outside of DC's characters and the Marvel Family. I certainly had no idea of the depth of the Golden Age. Then one day I was home sick from school and discovered Two Tub Man's cover site, and Bill Nolan's Pure Excitement Comics. I started The Golden Years site soon after that, and my Golden Age collecting and knowledge gathering exploded. By that fall I had a small handful of PD books and began All-Amazing Comics which was the catalyst for the collection I have today.
-Eric