Allow your cherries to soak at a minimum 6-8 hours or overnight in the refrigerator. You want the cherries to soak up as much of that alcohol as possible. Do note that the longer you let them soak, the stronger they will be. I have not tested soaking them for longer than 4 days, however, you can certainly do so as they will only soak up the alcohol to an extent (plus, alcohol works as a preservative).