I guess you could do it now...
The most important is the one at the end of the year, that one gets a good two cups of sugar.
but do it now, it won't hurt the bees, it knocks off the mites that are not in the brood...that why I do it again ten days apart, the ones in the brood will be out then, this does not achieve zero count during the year, but when the queen is no longer laying, all the mites are out...you get real close to zero. At least it keeps your bees from sharing the hive with the mites over the winter.