Obi Wan,
Lesson 1: Don't count on any timeline for upgrade. Whatever that is said or given WILL change. That I can guarantee you. It may change for the better or for the worse, who knows. There is no correct answer to your question.
Lesson 2: Fast track upgrades don't mean anything when EK has FOs eligible for upgrade above your staff number and there are loads.
Lesson 3: DEC's are always cheaper for EK to hire in a hurry than to plan for an upgrade from within the company. Since the company has demonstrated that it cannot plan its staffing levels within any form of efficiency, you can bet EK will always be either hiring or firing in a hurry. DECs are here to stay.
Good luck and yes some of the ranting threads here about EK are true.