Wait till you get the service, and then decide what to do. It's just put on your account. You're not paying it until you settle your bill at the end of the week, or if you are putting it on your charge card, not until your statement is due.
They don't charge it as $10pp per day. They put the whole thing on there. Makes no difference to me if it's there on the first day or the fourth. For some reason, it upsets some being put there up front. It's not like you have to go down and settle.
Whether cruising, or eating out in general, I expect to tip because I expect good service. Some people post like it's the luck of the draw.
And if I had lousy service, I wouldn't wait till the end to adjust my tips. They'd know about it right away.