Think it’s all about timing at BA as well as fleet choice. For example several of my ex bmi colleagues went straight in as Airbus captains when BA took over. Yet I know people 15 years in on long haul and happy to stay right seat as a lifestyle choice.
Outside BA totally different story took me 4 years to get my first short haul jet command and would have been sooner if not for industry stagnation due to the recession. Then straight in as a captain on a bigger jet in next job. All about timing and luck.
Whichever way you look at it getting your first command is a massive achievement especially at BA so well done.