By age 4.5 yrs the average whitetail buck is at about 90% or more of his growing potential. He really won't put on much more after that.

Genes play the ultimate role in total inches NOT age.

It's true they need the age first to realize the bucks potential.. but many 4.5 yr old whitetails never even make P&Y minimums.

If he ain't got the genes to be 150". He'll NEVER be 150". That's the way it is. Age will make no difference.. other than possibly getting closer to 150".