Very long time now. But with some breaks in between, where I just used Windows. My first contact was with SUSE back in.. I don't know, 1998 or 1999 it was, not sure.
Then used Red Hat for a quite some time. I remember that I never liked the aesthetics of SUSE and I really loved those Red Hat Icons and style. Felt in love with it. The gnome foot and everything. I still love the branding of Red Hat today, it just looks cool. I never touched Debian at this point, I don't know why tho.
Then from like 2000 to 2004 I used Windows only. But in 2004 it was Ubuntu time. And yeah, I felt in love with it back then. This was the time, when I also started using Debian.
And we all know what happened after Ubuntu was released. Many good things happened for Linux.
I used Gentoo for a year IIRC. Around 2008 or 2009. But was quite annoyed by it after some months. Those of you who know Gentoo, probably know what I am talking about.
Then around 2013 or was it 2014? I tried Arch. I think it was after they changed their install routine or whatever.
Then it was more like Arch / Manjaro until 2018/2019.
For my Servers I always used Debian tho, sometimes Ubuntu Server. Nothing else.