I look forward to reaching the next biggie with my post count, and I actually caught them in time in my first thousand or so, but now my trend is to remember until about 20 posts before, forget about it when the time comes, and remember again some 20 posts after. nd I am too lazy to go back and count the posts just to make a note in the end saying it's my n-th.
I recently missed my 4444, a post which I meant to post on this thread. I hope I remember to catch my 5000, but even more importantly, my 5555.
ETA: just realized I have a gross of reps!

Good thing I didn't miss this one at least!