Shortcut
You need to factor in the demise of the 767 fleet - all being replaced by 787s which arrive next year. The company has already said that the 787 will not mix shorthaul routes and thus expect that side to be taken up with Airbus equipment.
Although the changeover would take time you need to think how your career would progress if you delayed joining BA whislt waiting for a 767 place (which might never be offered)..............