The best place to start out is at your local extension office. Each county has their own rules for age, weight, and care parameters when it comes to market animals. In my county, they like to change the rules often, and only accept broad breasted turkeys for market. Be sure to attend any rule change meetings. As far as I know, most counties want your turkey between 4 and 6 months during fair, and there is usually a minimum and maximum weight. For an August fair, I would suggest aiming to get your poults in February. Broad breasted turkeys are very delicate, so be sure to have 4 or 5 poults, minimum. They find very ridiculous ways to hurt themselves. Be sure to use turkey feed, including a quality turkey starter for the first 8 weeks, and a turkey grower after that. Turkeys have higher protein and thiamin requirements than chickens. We have found that soaking rations in milk, like raw milk, or clabbered, or plain yogurt or kiefer, can help with feather condition and we did see less leg bone issues ( we have dairy goats, so had lots of raw goat milk or clabbered goats milk, or even whey from cheese making). Avoid too much corn, they already put on weight very fast and corn tends to be hard on the liver. Don't be afraid to ask questions!
FYI: The APA classifies all domestic turkeys as the breed Turkey. They are further classified into varieties.
