Where to place a pre-missile jet-aircraft boundary

If jet aircraft are included in the setting, should they be restricted to designs first flown between 1945 and 1950?

The panel would extend the gun-fighter window to about 1956, while noting that missiles add little disruption to a setting already containing much more advanced technology.

The proposed 1945-1950 cutoff is judged too narrow because gun-focused fighters remained important into the mid-1950s. The panel suggests roughly 1956 as a more useful upper boundary for a pre-missile jet category. It also cautions that the setting already contains flying ships, lasers, mecha, and magic, so missile-armed aircraft would not be its largest technological discontinuity. The answer separates a historically useful classification line from the internal balance of the fictional world using it.