You prove that you're capable of doing the job by simply doing the job without having the job title. Then when a position opens up (someone leaves or is promote

You prove that you're capable of doing the job by simply doing the job without having the job title. Then when a position opens up (someone leaves or is promoted) you're sucked into the position because you're essentially already doing it and have proved yourself. If you don't want to play the waiting game, you dust off your resume and find a place with the role that you desire. Whatever the case, if your goal is to get a promotion, you should really be discussing strategy with your manager. Part of your manager's job is to ensure your success within the organization - they'll have the best insight into what's possible, what you need to do to optimally position yourself, and possible timelines.