Clocks aside, you also have to be sure you've "logged in" after 12:01am EST, if you're on the site logged in before then you have to log out, close your browser and then log back in again and often that will let you do your check in then. Although recently for our trip in Feb, our check in window opened for first time cruisers and they were unable to complete the check in until 2 or 3 hours after midnight. Not sure it's it just overwhelming traffic causing the delay or what. It just appears to be an ongoing issue here and there.