I am also in central NY, and would treat this fall.  "Now" is not too soon and do not wait beyond sept. 15.

At this time of the  year, 2/3rds of mites present are in sealed cells.  Untreated, the females will leave the cells when the brood emerges.  With our recent 50 degree nights, the queen will no longer lay in drone cells, so the female mites will invade worker cells.  The workers hatched from now until the end of October are those that you need to take the hives over the winter...and they need to be strong, fully developed bees and not weakened and possibly diseased by mites.

The strips will not kill mites in sealed cells, so it is important that you kill all you can in the few days that they are outside such cells.

Lloyd
Lloyd Spear, Owner of Ross Rounds, Inc.
Manufacturer of round comb honey equipment and Sundance pollen traps