alternative to a tag when its not a specific person for timers

kinda weird question but ive only really used tags for something similar to this, but this time theres no way to know a specific person is gonna be on the whole time the timer is in use. for reference its execute as @a[tag=Timer] at @s run function stumsmp:increment and scoreboard players add @s Timer 1 (i definitely need to replace @s with something else too, not sure what) i just want to make a timer that only starts when a function is triggered. normally id give a tag to someone when a function is run, but not sure what to do here.