May I add one thing that would make your life much easier?
Don't just go through history chronologically, then art, music individually. Do it by periods! Start with history, then art, music and philosophy. History is the one determining why and when things are happening. This way instead of knowing things, you will have a global understanding of things and the whys.
example:
Renessaince, start with what happened in 1400-1600 years around the world. Then read the corresponding chapter in Gombrich's book, he is explaining in details why the previous style had to change in the light of history that you just read. Then I'm sure you can find a similar book on music history (please someone who's into music recommend one ❤). And so on with the other subjects.
This is how I learnt from high school, all our teachers being on the same page for history, literature, philosophy, art and music. So for those months we were totally immersed in the era.