Thanks for your answers. Im obviously not used to all that computer/software stuff. However I think I'm starting to understand.

So if I understand well, the registration code I entered (the one which added "Stormblood" to my Mog Station frontpage) will grant me access access to the game on the 16th instead of the 23th - right after the 15th&16th maintenance. I will probably receive the game package itself for the 23rd but it looks like it doesnt matter then - as long as Im getting it before the 23rd to get the "definitive" code.

My only remaining concern then is about the way to get the "game data" or whatever it is for the 16th, since I wont have the disc on the 16th. Will it download automatically or something? Or maybe the reg code is enough and no data will be required?

Sorry again for the silly questions - im definitely not good for all this