Not gonna lie, We start shooting bucks at 4.5. All the research I have found shows that a buck's biggest antler growth is from 3.5 to 4.5. Second biggest jump is 4.5 to 5.5. The odds say he won't put on much next year. Of course the research shows the majority, there are still some that blow up at a later age. Where I hunt a 2.5 year old is lucky to make now but we refuse to shoot anything less than 4.5. A deer is biologically mature at 4.5, that's what I'm looking for. Hopefully he is one of those late bloomers and he blows up for you. Good luck with him next season.