Twitter says I joined it in March of 2007. My earliest memories of it involve interacting with it completely via SMS. I think I had a google voice number registered or whatever. You could specify keywords you were interested in & any tweet featuring one of them would get sent to your number.
Possibly some of that is confabulated...
@rpardee I do not miss the days of flip phone typing Twitter replies.
I recall I was learning ruby at the time & so made that one of my keywords...