My first comic
I don't know how old I was, but it was at a point before I could read when I came across a stash of comics belonging to (I think) a relative. I don't really remember the details, but I was attracted to the colourful and exciting pictures, which were so much more dynamic than anything available locally. One of the comics here may have been Action Comics #324. I couldn't say for certain, but it's the earliest comic I remember.
There was something about Supergirl growing horns and becoming evil that stuck with me. That and the issue of Wonder Woman where she grows to giant size and eats a big pizza. If I had an analyst they'd have a field day.
Is it any wonder why I have a thing for silver age DC?