Greg,

I’m glad you phrased your question by starting with “on average…”  Each buck is an individual just like humans.  For example, I was the tallest kid in my first grade class.  However, I didn’t even make the freshman basketball team.  Different individuals (human or deer) will express their growth potential at different ages.  However, Mississippi State published the following data years ago that represents the average amount of antler growth potential expressed by several bucks in their research program.

I suspect the trends would apply to free-ranging, wild herds as well.  There is no doubt about it, allowing bucks to mature to at least four years of age will allow most bucks to express more of their antler growth potential.

Growing Deer together,

Grant