There are no solutions to your problem.
RO2 is exclusively Steam-related game, so Steam is in controll of it: installs, updates, unlocks etc.
So if Steam says that you have to wait- well, just wait.
What you have on the disc you bought (and I'm guessing here, but what follows is logically most accurate):
- sounds
- textures
- in-game movies
- maps
- 3d models
- etc.
What you don't have (and this is what one of the game developers actually stated):
- game binaries (game code in other words)
This is to prevent "0 day piracy"- game being stolen from stores and distributed on piratebay before official launch (tho in case of such a multiplayer game as RO2 it's rather irrelevant).