When does the story end?
The final countdowns start with particular quests. They are not a single fixed day on every playthrough's calendar.
Beholder
Finishing the conversation in Completion report starts Change is coming: 120 in-game hours (5 days) before the final Ministry call.
The following Pick up the phone quest has a 5-hour response window. Letting that timer expire triggers Carl's arrest.
Blissful Sleep
Completing the Ministry conversation in Pick up the phone starts I don't want to die, with 336 in-game hours (14 days). When it expires, the story enters its ending checks. This is not a guaranteed death exactly fourteen days after starting a new game.
Reading the quest clock
These durations are the starting timers, not the time remaining in your save. The journal rounds remaining game hours upward. Pausing stops the game clock; loading a save restores the remaining countdown.