Hi, I had a torn and almost detached right side rotator cuff and like you am a lefty! Up here in Canada had to wait almost a year before getting it done so attended regular therapy sessions to keep the movement active. It took about three months before they allowed me to ride again and said if I messed it up again that was it no repeat op! Been fine since a couple of weeks after the op attended more therapy after the op and am happy to be back riding without issues.
Mike S