You can't do that, as the minimum time for a rally is 5 minutes. The point of that is that a rally is a great way to have multiple players join your rally and go to a specific target, like a base or events' building or rebel camps, and during that time, the players that rallied can set up and choose the troops they want to send on that rally. You can activate the lone wolf skill, immediately ending military rallies.
* Note: This skill only applies to your rally.