A matter of hours, minutes, etc.
Definition 1 of 2

Impending Event
Use when something is expected to happen soon, highlighting its urgency or importance.

The storm is expected to hit the coast in a matter of hours.
Imprecise Timing
It's not for exact times but for when an approximate duration gives a sense of soonness.

He'll be here in a matter of minutes, so be ready.
Emotional Urgency
Can convey a sense of excitement, worry, or other strong emotions linked to an upcoming event.

Her performance begins in a matter of minutes!
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