Blizzard explains on the forums that it will not immediately be available upon release. They do not, however, say that it will open at the same time for Europeans.
Due to the fact that we will be delaying the release of patch 3.3.5 in Europe, Korea and Taiwan in order to ensure the patch process in all regions is as smooth as possible, the Ruby Sanctum will not immediately be available on North American realms upon the release of the patch. Once patch 3.3.5 has been released in North America and we are confident about a time when we can open up Ruby Sanctum, we will provide an update here on the forums.
Links
WorldOfWarcraft.com - Source
