Fruit woods season very quick, depending on the weather, especially if cut to the size you're gonna use for smoking. If I cut some green apple to chunks around here right now I'd expect them to go "clack!" when knocked together and be ready in three or four months, tops, as long as I kept them dry and with air circulation, of course. You risk mold growth, depending on the climate, but it will season really quick if left in a shed in the warm months.