First posts almost invariably show in the queue of the same name within 15 minutes or so, and sometimes nearly immediately. Occasionally, however, when looking at the First Posts review history or reviewing some myself, I’ll see a post from days or weeks previously.
For example, this reviewthis review was done on September 23, but the post in question was made two weeks previously, on September 9.
Why are such old posts showing up in the First Posts queue?