That YVR trick has been played for years. At least three that I know of, when it was done to my F/Os. It is way outside of the Roster Disruption agreement, and is rostered when the flight is uncovered. This is one that the AOA should attack.
As to the thread title, from anecdotal evidence, very short.
It is the subtle things. How stable is your roster compared to two years ago? Listen to the tone of the crew controllers voice, how stressed are they? Recently I hear stress. Ask around, how are your colleagues rosters? How much overtime is both rostered and flown? Seriously high overtime pay is being paid, which is a total anathema to a schedulers mind.
Best that can happen is overtime. Worst you already experience, so I shall not enumerate.
What to do? Collate the evidence, use it either as support in negotiations, to CAD to show non compliance, or to the lawyers for a civil court case.