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.

Good Luck!