Try to do all the study required before you start the sim and line training. i.e the only things you should learn during the training is what you didn't know that you didn't know.
I wrote a four page checklist of the topics and material I wanted to study for the command and then systematically wrote an A5 binder full of notes with references to the company manuals. For my last year in the RH seat I asked all my Captains what they would recommend and added those to the list. It was great because I knew where I was during the study process and it gave me the confidence to know that I had covered everything beforehand. The whole preparation process took about 6 months.
The training is hard enough without staying up till 3am studying after a grueling day of flying in an unfamiliar seat.
Good luck and best regards
