Palo (no "s" on the end) is generally only open for dinner. On the 7 day Magic voyages they also offer High Tea and Champagne Brunch on select days. (These are not yet offered on the Wonder.)
I believe the reservations are done on the hour and half-hour. So, you could select 5, 5:30, 6, 6:30 etc. I believe the earliest reservation is 5 or 5:30 and the last reservation is 10 or so. (Not 100% on this though. Perhaps someone else can be more certain on this aspect.)
If you've never been, Palo is an experience you won't want to miss! Enjoy!
Jason