Each sticker is worth 500 miles, not 800 (that's DL). Also, there is a 50 mile grace per flight, so 1040 mile requires 2, not 3.

Finally, if your advance request doesn't clear, there's a separate list when you check in at the airport. Occasionally, you may get upgraded here even if your advance request failed, since they hold a couple of F seats for last minute paying walkups.