This is true for any of the WDW resorts. If you do not have the letter by 6pm-ish, check with the front desk and they should be able to print it for you.
We usually get the letter about 7-8 pm the night before the cruise. We've been picked up anywhere between 10:30 am and 12:30 pm. Luggage has always been picked up at 8 am on the morning of the cruise, though you don't need to be in the room.
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