Since a jacket and tie are required for the Olympic Restaurant choosing a semi-formal night would make good sense. On a 7 night voyage I believe the 4th night is semi, but you could double check that once you're onboard.
Here's a link to an article I wrote about our "Olympic Experience"... http://www.cruisemates.com/articles/...nniumlive3.cfm
Kuki has a very good point. Another good night to book it is the first night onboard....just because it won't be difficult to get reservations for that night. In my opinion, ANY night is a good night for the Olympic Restaurant. It is a must do.
Mary Lou Scanlon
NCL Pride of America April 24, 2010
NCL Epic February 12, 2011
RCCL Allure of the Seas - September 18, 2011
Celebrity Eclipse - February 11, 2012:
RCCL Navigator OTS - February 9, 2013
There are all sorts of theories, mostly having to do with haberdashsery, sea days vs. shore days, lobster night in the regular restaurant, etc.
But the simple fact is that the food in the Olympic (and in its counterparts on the other ships) is better than in the main dining room on any night. If you can pull it off, go twice. More than twice is gilding the lily in my opinion (too much of a good thing in too short a time).
Don't spend too much time agonizing over which night. Just go.
We just got back from the Millennium 11 night cruise and ate in the Olympic Restaurant. We chose the semi-formal night, on a day when we wouldn't be too exhausted from excursions. It ended up being the night we were in Panama. We made the reservations late enough so we wouldn't have to rush, yet gave us plenty of time to feed the kids beforehand. The show that night was something we didn't really mind if we missed (not one of the big extravaganzas). We lucked out and it was the perfect night to choose. It was well worth it and the waiters were wonderful, very friendly and accommodating. We had no trouble at all making the reservations, it was one of the first things we did when we got on the ship. The night we ate there people were booking for other nights, they still had openings available. Enjoy!