I think the flight numbers were first used on stamps when the groove came out. A few discs with the older swoosh logo had the flight numbers on them, such as Champ Wraiths, Destroyers and a couple others.
The chubby swoosh logo came out in April or May 2010, and all of the discs that are stamped with that have flight numbers on them.
The chubby swoosh logo came out in April or May 2010, and all of the discs that are stamped with that have flight numbers on them.