The servers almost always ask us if we're on the DPP when we sit down, but sometimes we use our DDP credits and sometimes it's OOP. Many times, we scope out the menu to see what we'll order before we go to see if it's "worth" using the DDP credits or not. You don't have to decide until you get the bill (which is handy in deciding sometimes!) but be sure to mention if you plan to use the DDP or not when you pay - if you give them your room key/card to pay, they may charge your credit card and not deduct the DDP credits or vice versa - just make sure you tell them!