@Nightowl11 I finally found my letter, but don't know how to attach a picture.
All-aboard on turn-around day in Seward is at 7pm for an 8pm departure. If you're going ashore, they ask that you depart prior to 9:30am, with re-boarding no earlier than 11:30 (or whenever the ship is fully cleared and ready to receive guests). This was for the 5/17/24 turn-around in Seward, but I can't imagine that it will change much.
As suggested, go to the meeting the day prior to Seward and they will answer any additional questions.