Most biologists I have talked to say the majority of antler growth was completed a week or so ago in early August. Now during mid- and late August, antlers are hardening. In early to mid-September the velvet dries and is shed, usually in only a matter of hours.
BTW, the cue for the antler hardening and velvet shedding is the change in photoperiod caused by increasing darkness and decreasing daylight, which results in a buck’s increase in testosterone.
And which means hunting season is right around the corner!