We were on the Viking Jupiter in May and the ship was almost full (880+). Their advance reservation system wasn't working properly and all advance ones were lost which we found out on board as they didn't show on our calendar. However, they were able to accomodate us for both venues. Also, as stated above, one can make reservations fairly easily which we were able to do. Can call during certain hours from your room, at The Restaurant during certain hours and at the desk near the hand-washing station in the World Cafe. We found the latter to be the easiest. Do it fairly early like we did and we were able to get our first choices for both restaurants and our preferred times. On our cruise, the Chef's Table was not as popular as Manfredi's. Have a fun time!