Spades is correct - you have to have a bona fide tentative offer letter in hand for the "age clock" to stop. Its called the "in process rule."
Military service is irrelevant, even as a controller. The key is that the definition of a controller (5 USC 2109) specifically says civilian in DoD or FAA (and FSS counts). Former military controllers are subject to the age 31 rule because they've not been previously appointed as a civilian controller in DoD or FAA.
Here's the relevant law 5 USC 2109
For the purpose of this title— (1) “air traffic controller” or “controller” means a civilian employee of the Department of Transportation or the Department of Defense who, in an air traffic control facility or flight service station facility—(A) is actively engaged—(i) in the separation and control of air traffic; or (ii) in providing preflight, inflight, or airport advisory service to aircraft operators; or
(B) is the immediate supervisor of any employee described in subparagraph (A);