I kept track of the days for about the first six months. Now, if I really want to know, I just plug the date into the soberiety calculator. I find this helps give me some perspective on my recovery progress. BTW, today is Day 660 for me!
As for posting milestones, I love to see it. In fact, the VERY first post that I ever read here was someone posting about one year sober. That really got me thinking that WOW...I'd love to be able to say that someday. That was nearly two years ago
