I've been using Wikipedia since 2005, subsequently making my first edit in March 2007. Then, after over a year of contributing anonymously (pretty much just minor copyedits, adding links, etc), I finally registered an account in June 2008. I previously edited under the monicker "Master&Expert" (see these two links for more on that subject), but I had my account renamed in August 2012.
If you want to know more about me, you can find out all you need to know here. A matrix of my accounts on other projects can be found at this page.