I agree there really is no such thing as a 1-2 year old cull buck. But I would say by 4 if he is a big wide 4 point or something that is just really u impressive he more than likely is never gonna be. Seems like I read that most bucks have achived 80-90 percent of antler growth by age 4. If that is so there is really no reason not to shoot that 90" 4 year old. I wouldn't call him a cull, just a 4 year old that didn't have much in the antler department.