You want to stop a lot of medications, herbals, supplements, that sort of thing probably a week before and, at least, a week after. In general the real danger to you as far as healing goes is going to be tobacco, nicotine, vasoconstriction, poor blood flow to the area where you've had surgery. It's best to be safe than sorry and just toke up and smoke your weed some other time. Just don't do it the week before and the week after.
Do I Need to Stop Smoking Weed Before My Procedure?
Dr. Chase Lay explains the suggested restrictions on smoking herbals before and after surgery and the potentially harmful role it plays while the body is trying to heal.