Hi Kurimaw,
You dont have to go to specifics now, like which Aircraft you will read and study, since you're not yet there in Flying stage as you've said. Instead, I suggest you try reading Subjects or Articles in relation to Theory of flights, Meteorology, Aviation Medicine, and lots more topics that are useful for the enhancement of your knowledge in this field you are aiming at.
Reading a full length of the 747 Operations Manual or any type for that matter,wont do you any help in achieving this Career. You can do all this when you get there and its best to learn through a Human-Machine interphase or Hands-on.
Jc