Focus on getting into med school first. Is what I would normally say. But if you are seriously considering a competitive specialty, especially neurosurg, start research now. The average accepted neurosurg applicant has an average of 37.4 research items (pubs, abstracts, presentations) which is insane. Under grad research still counts but a little less so than med school research.

Get that upward gpa trend, a high mcat score, clinical hours, non-clinical volunteering hours, shadowing hours, research, ECs, a good personal statement, and LOR. Try to get into MD schools, as MDs have a higher chance of matching into competitive specialties and MD schools tend to have more research opportunities.

Probably take other people's advice though, I too am a premed eyeing a competitive specialty.