To get jobs, you need to qualify the recruitment tests and personal interview round.
Highly Preferred recruitment Exams are
- IBPS PO Recruitment Exam
- SBI PO Recruitment Exam
- RBI Assistant Recruitment Exam
- IBPS Clerk
- SBI Clerk
You cannot give bank exams after 12th immediately. The minimum eligibility to get a bank job is graduation. After 12th, I would suggest that you should complete your graduation like BBA, BCom as per your interest to apply for the banking jobs.