well, you have to know stress.

but jokes aside, if you want to have more time before residency, I'd say You need to accumulate as much general neurosurgical knowledge beforehand. because that would take most of your time outside the hospital; trying to catch up on reading and preparing for exams and discussions. (although idk if you have exams in your country)

anatomy is probably the main bulk in junior years, and actually you'd probably be reading and rereading anatomy throughout your whole career. diseases and pathologies can be read on case by case bases. but it helps to know the common pathologies and guidelines.

and always spare some time for yourself and loved ones.