There are basically two or more hours until Diablo 3 will start for Europe. The announce from the login screen is saying that the players should be ready to play at 00:00 AM, CEST time.
CEST means “Central European Summer Time”. Currently in France, it is 21:54 PM, CEST. So just two more hours until Diablo 3 will start and players can login to play the game.
Romania. 01:00 AM (after CEST).
UK. Right now in United Kingdom is 20:57 PM. Diablo 3 will start in about 3 more hours.
Holland, it is now 21:57, the game is about to start in 2 more hours.
Italy, it is now 22:00, the game is about to start in 2 more hours.
You can use this website, timeanddate.com to track your location and check the CEST time, basically the game will start for your country in two hours if you are around France.
What is important is that the servers can hold such a high amount of players once the official starting time will arrive. The open beta weekend brought many problems and if we remember the starting of all the World of Warcraft expansions, all the time the servers crashed.