14-21 days after your last AAS shot/dose.
AAS can interact with the anesthesia and horrible things can happen (like being put under and never waking up). From what I have read, lethro, clomid and nolva do not have any effects on anesthesia. AAS do though. As a safety measure I would discontinue all substances 14-21 days prior to surgery just to be safe. Some OTC drugs, like aspirin also cannot be used because of its blood thinning properties.