You won't be able to cash out your winnings on the day you disembark.
If you plan to hit the casino, be sure to redeem your money and settle all outstanding balances at guest services on the last day (aka the day before you disembark). Any unclaimed balances that are less than $10 will automatically be donated to St. Jude Kids; if your balance is greater, you'll have to wait for your check in the mail.