It really depends on the calf and how good you want them to be. I have caught and halter broke calves 3 weeks before the county fair, and I have fed and worked hair for 4 months before they leave the farm. It also depends on their weight and your target weight for the fair, how well mama is milking, forage, etc. Right now we have calves turned out on pasture with their mamas still at 9 months because we have more grass than cattle to eat it for once and the cows are still milking really well. These calves are getting halter broken while still nursing, gaining almost 4 pounds a day, and will go to their first show in early August