Oh, I've dug into this, so I have very exact dates actually haha.
It was the spring of 2000, I was 9 years old. The anime started airing on Swedish TV4 on Saturday March 4, but it was on at 8:35 and just I wasn't a morning person so I never really watched the morning cartoons.
Instead it was the cards that got me into it. They must have become really popular after people got into the tv series. I remember Team Rocket being the "new and cool" set, and that was released April 24 in Europe. My mother always kept very precise records of the family's expenses, and on May 6 her notes says "Pokémon 28" - which is what a booster pack cost here at the time. I don't know if that was my very first cards, but certainly some of the earliest. I remember I got a Pikachu in my first pack and I was so happy!
The Pokémon craze must have receded a bit in autumn, but in early 2001 I got to try my best friend's Blue and was hooked. I got a purple GBC and Pokémon Red on January 13 (again, my mother's economy notebooks - it was 1098 SEK btw) and the rest is history ...