I probably played with some Ubuntu live CDs beforehand, since you could order them for free, but the first time actually using it was back in 2004-2005. I had gotten one of the first AMD 64 bit laptops, with 32 bit Windows and I wanted to see what 65 bit “could do”. So I installed Ubuntu as a dual boot setup. Worked quite well! I played around a lot with customising the experience, making my desktop 3D with Compiz. Great times! I also remember the lack of game support it had, I could only play OpenTTD on it. How times have changed! I’m now running Linux full time on my game machine (EndeavourOS) and haven’t touched Windows in a long time.