The timer starts at the moment when the button becomes white (first frame) https://imgur.com/ETJdxs0

The timers this ends at the moment when the button becomes white (first frame) https://imgur.com/fGnPs3q

For mission destroy ennemie core it first frame when the core explode or white first first frame of white screen

The timer start at launch in menu. the menu must be seen at least 1 sec to check if you are in default loadout or not