Its going to be fine. You should reach out to the program to see if you can get on some research now. You should be doing research, trying to go to their didactics if you are still an m2.
It literally will not matter, because if your clinical rotations would not let you rotate with them during your surgery rotation, its not like you would be able to build relationships with the department anyway.
You should have some electives during Y3 rotate with them during that time.
Somethings and skills you can pick up on even without rotating there
-single handed ties- this is the tie of choice for neurosurgeons at the institutions i have rotated with . Have this down, comitted to muscle memory, most of this work will happen outside the rotation anyway.
-Anatomy
-Neurorads
-Neuroexam
In reality you will have no skills that will wow them either way, You are an m3/m4 you will be expected to show interest, put in long hours, know somethign about the procedures/anatomy, and basically be a person they would want to be around for 7 years. No amount of extra exposure will give you that information other than doing well on all your cores and genuinely being a reasonable human being.
If you are still gung ho you should try to shadow during your time off in m3.
And most of all ACE YOUR STEP ONE.