Hilton used to use "quarters", but no more. The just start and end (and sometimes extend) promos whenever they want. to.

The promo names may still have a "1Q" or whatever in them, but if so that's just a holdover from when the promos actually aligned with quarters, nowadays if a quarter is mentioned it's just a name and doesn't mean the dates actually align with a calendar quarter.

For example, the current 2x/3x promotion started at 2x in Sep and went to 3x (mobile) in early Oct and was originally supposed to end Dec 31, then it got extended to Jan 31. No one yet knows whether it will truly end on Jan 31 or simply get extended again. The (stackable) current 5000 point promotion was always supposed to run Nov 1-Jan 31, so it never tried to align with a calendar quarter.