On its earliest days of 777 operations, British Airways flew on a regular basis the very short LHR-CDG sector, between the introduction and ~1997. Alongside
BA introduced the 777 on Middle-East, one of the market primarily planned for the type within the airline.
This was performed in order to get the required crew training AFAIK.
Photo © Bernard Charles
Here is BA 777-236 G-ZZZA at Paris - Charles de Gaulle (CDG)
Air France, unlike the A340 and 747-400, introduced the aircraft on longer routes: CDG-CAI, CDG-BEY and quite a few training nonr-revenue flights were operated on Châteauroux (French airfield for yet-to-be broken-up-aircraft and crew training for BA, KLM and
other airlines). Also, there are regularly non-revenue operated on small French regional airfield.
Photo © Sebastien BOUTRY
Delta Air Lines
Delta Air Lines introduced the 777 on ATL-MCO, one of the airline' most popular routes, and AFAIK well-suited for crew training.
Photo © Sebastien Boutry
Would anyone have other examples at other airlines about the earliest days of operations, or more information about these above please?