My only age assumption is that he's 2 1/2 or older, although if forced to "guess" his age, would go with 2 1/2.
I know antlers do not equate age, but some generalities provide clues when those antlers are about all you have to aid that guess. That said, note the lack of any mass, which would lead me to believe more likely 2 1/2 than older. I am assuming this buck is still in velvet regarding that "lack of mass".