What is the length of time in service needed to qualify for short term tax loophole?

[Nicole Patching]

If a property is purchased and renovated to be a short term rental in the same calendar year, how long does the rental need to be active in service (i.e. on Airbnb) to qualify as a short term rental for the short term rental tax loophole (putting aside the material participation  and cost segregation study that are also needed)? I.e. If I were to purchase a property now, renovated it and get it up and on Airbnb in December with active rentals happening during that month. Would the propery be considered a short term rental that, should all other requirements be met, and a cost segregation study performed, to qualify for the short term tax loophole/bonus depreciation?