I like the idea of not showing visible timers (just anxiety causing) but showing the influence spheres in very trackable ways. Maybe if the standoff was highlighted by some kind of border intensity where they met or other stuff that made it more obvious where the player's actions were influencing the war.
Maybe there should be a strategic 'war-room' view of the starmap that not only includes spheres of influence and last known locations of fleets (friend and foe), but also the latest intel, from your commanders as well as allies. So, like mentioned in above posts, there are no timers or clocks, just firm statuses or possible indications on what the current situation is, what the situation is moving towards, and how fast it is currently changing.
War never occurs like clockwork, it should be fluid and unpredictable - to the point where replays are never the same given the exact same circumstances.