Ah, now I understand. You want just a one time countdown timer for the fan, but not every hour.
You could sort of do that by setting the time per hour in the cycle function, say 15 minutes, but leaving it set to Auto until you want that 15 minutes to run in which case you would turn on cycle mode. The drawback to that is you have to remember to turn it back to auto sometime after it stops or it will run again next hour. Worse case if you forget is it would re-run your set time each hour until you remember to switch it back to auto. Certainly not what your looking for, but a workaround until they possibly add the function you’re hoping for.