Double bypass, heart valve, pacemaker. My doctors advised me that shooting pistols was fine after 4-6 weeks depending upon how I felt. They advised not shooting heavy recoiling rifles or shotguns for 6 months as the "breast bone" area is held together with cartilege and that takes longer than bones to heal.
Following their advice, I had the surgery in August. I started shooting pistols in October, shot my .223 rifle in mid-December, and shot my first 25 shot round of trap in late January.
As pointed out, everyone is different. If I were you, I would not be in a hurry. As my surgeon pointed out during our conversation on the subject of shooting - "You really don't want me going back in and having to wire your breast bone together." I would be cautious, and err on the side being conservative.