If you are flying domestic, have Pre-check, and no bags to check, and are using a taxi or Uber, 11:00 should be a very safe bet. If you are using a transfer from the cruise line, they may not allow it for anyone leaving before 11:30.
We had a cruise in the spring where the ship's clearance was delayed and disembarkation didn't begin until close to 9:00 for the first walk-off group. I wouldn't book anything earlier than 11:00 for domestic or 12:00 for international unless I was comfortable with dealing with a missed flight.