You got the 1000th post.
You don't have to make it, you just get first crack at making it should you want to.
The general rule of thumb is that the 999th-post-maker is next in line, although that's generally if the 1000th-post-maker disappears or forgets to make it or something, so if you wish to bequeath your thread-creation throne to someone other than azzaman, that's probably okay.