16 notches in the gauge position from fully closed. Seeder wheel is about 1/4" or so away from the sheet metal side.
Measure off an acre and test it. Put in a 50# bag and go with it. I know you will have to stop frequently to ensure the seed is in the trough to the seeder wheel, but an acre isn't all that big and won't take you that long.
For a 7' drill (actual seed dropping part) it is a strip 6200' long. For a 9' is 4840'. A mile is 5280'. If your field is 1000 ft long, it's about 6 laps or 5.