Like many things carnival it depends on the ship and its willingness to move forward on your behalf. We turned Diamond on the 2nd day on leg 2 of a back to back. We asked and told they would look into it and on day 3 no change or response so checked again. Told that “until” the system updated showing our points from the 1st leg they could do nothing. Completed the cruise without being upgraded to Diamond and sailed 2 more times before finally getting it corrected. Read many stories of success but sadly it simply doesn’t always work because of the las k of willingness of a ship to complete the process.