First time I got my hands on a Linux distro was back in 1997. when I got Slackware on a magazine's CD. I've already used Solaris on a university server, so I found it quite interesting to have a unix at my pc too. Unfortunately, all I got was a similar experience to telneting the Solaris server since I couldn't bring up X on my Tseng ET4000 videocard, no matter the amount of fiddling by me and a friend who has already been using Linux.
About the next year, I got Redhat the same way, but I didn't like it - with KDE it seemed too much Windoze-like, and too little Unix-like to interest me :P
In 2000 I was introduced to Debian and I started regularly playing with Linux afterwards. For the next several years I've made several experimental installs mostly on laptops (it was a pain to set up the soundcard on them because practically all of them had some dreadful ISAPNP ones). From that time I mostly remember configuring and compiling kernels most of the time.
During that time I also registered myself as a Linux user on The Linux Counter.
Distributions I used were still Slack and Debian.
In 2007 I've made my first Linux install for daily use, I had another elderly laptop at work which had only 192 MB RAM. It originally had Windoze 98 which was quite unusable these days, so I installed Xubuntu on it. It worked perfectly! I dare say it was more pleasant to use than some newer machines with much more RAM and newer distros. The next year I got a new laptop with Vista, which I tried for a few months and then, in disgust installed and started using Linux on it. From that time on, I very rarely dual-booted to Vista, until some day I destroyed it completely.
My primary OS is Linux since then.
I'd like to say thank you, Micro$oft! Had you not released Vista, perhaps I'd still be too lazy to convert to Linux for daily use, as it has been when I had 2000 and XP.
So, what year should I put in the poll? Was it 2007/08 when I started using Linux regularly? Or should I say 1997. when I installed it for the first time? I believe 1997 will do, since then there never was a year without doing at least something with Linux. All that time I have been quite confortable working in the shell, and compiling kernels, so I guess that counts.