Depends on your lease, surrounding pressures, goals winter mortality risks etc.
He is likely not topped out yet (or at least what I see from the picture body wise) but man he is pretty so...
If he has a g4 on his right side (can't tell from pic) he will likely touch the high 130s possible 140.. I would guess 4.5 yr old. But all this is just a guess from a single picture so it could be off.
Any more pics?