You didn’t say but we’re assuming you had surgery to repair the torn tendon. If that’s the case, it’s likely you’ll be in a cast or cast boot for 10 days to two weeks after the operation.
Some doctors transfer patients to a rigid orthosis (brace) with a heel wedge. This keeps the foot in slight plantar flexion (toe down position).
About the time you can put full weight on that side, the heel lift is lowered to neutral. Patients are allowed to return to regular shoe wear around six weeks after the surgery. This includes cowboy boots.
You’ll need to keep up your stretching exercises since most cowboy boots have a one to two inch heel. Usually the goal is to have equal range of motion at the ankle on both sides. Patients can return to normal sports and activities when motion, strength, and endurance are similar to the uninjured leg.