I liked it from the first time I heard Girls Generation in 2007 and I started listening to them regularly after they dropped 'Genie' in 2009. That was a different time though, there was no official YouTube content or social media presence and Korean variety shows were unheard of where I live so I can not exactly call myself a 'Stan' by todays standards, it was basically just the music and MVs and that was it. I only discovered Girls Generation because I was playing Starcraft with Koreans and some of them were really into it.
My horizons didn't broaden until Twice dropped 'Likey' in 2017 and it went "viral" in the west, I immediately looked up other MVs by that group and found 'Signal' which I didn't particularly like so I sort of put K-Pop on the back burner again but I would be more regularly exposed to K-Pop and listen to occasional random songs but it wasn't on the level where I knew the name of group members for a while yet.
In 2021 Twice came to me again while I was going through a tough time in my personal life, that time was all a blur but I remember that they were in the middle of 'Scientist' promotions at the time. I was just lying in bed and 'Likey' kept playing on repeat in my head (4 years after I had seen it) until I looked it up on YouTube and then the algorithm did it's thing; I was suggested a few TTT's at first and it snowballed from there until I had seen all of their content and gone to see them in person.
In hindsight I think my brain was trying to show me happy things to cope with what I was going through and I find it interesting that even though I wasn't that into it and hadn't seen this video for years my brain had subconsciously recognized it as something wholly wholesome and filed it away for a rainy day. I gotta say.. It worked like a charm. I'm in a much better place these days and K-Pop (especially Twice) helped me get here so they have a fan for life now.
This turned into more of a summary of my story instead of an answer to a simple question so TLDR; I was 18 in 2007, I was born in the same year as 6/9 SNSD members!
(Just look how happy they are!)