How soon after my surgery can I start wearing a breast prosthesis?

Depends. That really depends on what kind of surgery you had. Generally speaking healing takes 4-6 weeks. If you had a mastectomy you should be good to go by then. Radiation may change that answer. There are a lot of variables!
Ask your Surgeon. Typically, it is safe to wear a prosthesis within 1 to 2 weeks post surgery. However, you must consult your own surgeon since the nature of the operation may dictate when it would be safe to start using the prosthesis.