Shedding is affected by photoperiod, nutrition and genetics all of which affect the hormone balance that triggers shedding. Most in the rockies will start losing antlers in mid to late February, but others in the same area could drop in January, while others won't drop until mid March. They don't normally shed both sides at exactly the same time, which is why it is rare to find matching sets. But they will shed within about 2-3 days of each other.

what do you mean photoperiod?

thanx for the reply by the way
very insightful

I believe it refers to the amount of daylight to which the deer is exposed.

Or maybe it means that period of time when hunters review their trailcam photos and wonder why they never saw those big bucks captured in photos

Nah, I think it is the former.

Yes it means the length of daylight. Nature uses photoperiod to trigger many seasonal reactions, rather than just weather, as a cold or hot, or wet, or dry spell could be disastrous if that was a plant or animal's sole indication of when to rut, drop leaves, produce seeds, drop antlers, grow a new coat of hair, shed current hair, etc.