I'm not sure when I first read my first longform comic. By "longform," I mean "comics where the stories are more than five pages"; I grew up reading British anthologies like The Beano and The Dandy and Whizzer & Chips (I was a Chipite. Somewhere, someone on the internet knows what I'm talking about, and read that with a feeling of "I knew he was a Chipite. I hate Chipites!") and Buster, and in each and every case, comics were short things of some kind of possibility.
Part of the reason for that was that the first comics I read as a kid were humor comics, and things like "story" came a very far second behind a mentality best described as "Tell the joke and get offstage as soon as possible" (It's fair to say that, later, 2000AD worked on fairly similar lines, in a weird way: Get in, get to the point, get out and don't stop in between). Looking back, there's such an... I want to say "economy," but I'm not entirely sure if that's the right way of putting it... There's such an urgency in those strips, such a feeling of "don't waste anything" that, looking back at it now, after decades of reading the more relaxed, conversational American format, seems kind of mind-boggling, like finding punk before punk existed or something.
(A year or so into The Beano, I graduated to library copies of European comics like Asterix and Tintin, which were another thing altogether, much more relaxed and spacious. I remember being surprised that the stories kept going and didn't have that page-long rhythm, punchline following punchline and is that a plot?)
When I think back to those old comics - and the weird way in which what I've come to appreciate so much about comics now, be it character, dialogue, inventive panel layout, distinctive art, whatever, was almost entirely absent from them - I wonder what it was that hooked me, so. I can barely remember the names of the strips in each comic, never mind the creators, and I don't even remember really enjoying the stories back then. There was just something about the form, some possibility I was convinced was in there somehow, even if I didn't know what it was, or wouldn't really see it fulfilled for more than two decades afterwards.