I'd band him and then wait at least 90 days before butcher. Got to remember though there is now a "cut off" time as to when a custom butcher can come out and do the deed, least there is here and I think it is around 30 months. They will mouth him to check the age. If over I think 30 months they will have to bone it which costs more. We have it done on our ranch. Saves money over sending it to the butcher cause they can leave the head, feet, tail, and insides you don't eat out in the pasture. Less stress on the animal as well which I think makes a huge difference in taste.
About 2 years ago I had a bull that was around 30 mos. that we had done. All grass fed except for just a bit of cracked corn every day to keep him coming around. He tasted great.
J