Why don't you just have the percentage to win a map change on a timer.
EXAMPLE - not real numbers here
1 Hour in - requires 99%
5 hours in - require 85%
and so on.
Let’s keep it simple.
Hitech is onto something here.
That said, 99% could be a trigger to win somehow...total victory like Axis & Allies the board game.

Knowing what it takes to win is confusing to new players. Even some of us who have been around awhile get ADD thinking about it. A clipboard graphic showing bars or something to visually represent how close one is to winning a map might be helpful.