Accounting & Commerce

Well, you should do a professional course related to management field. There are several private and government institutes. As a prudence expertise, I recommend you this.

For those destined to become an MBA holder, any graduation will do. Any graduate with 50% aggregate through the clearance of eligibility test such as CAT, MAT, ATMA-AIMS, CMAT, etc. As applicable to the institute of study become eligible for admissions to an MBA programme. For those with a B.Com degree, MBA with Finance or Banking and Finance are good choices.

Which entrance exam are you talking about for commerce? I assumed that you are asking for 12 board Commerce exam. I am attaching the link please find the papers in the given link:
https://www.vsijaipur.com/class-12th-commerce-papers/.
Best of luck.

After having a look at your percentage, it looks pretty tough for you to get admission in MBA. Whereas MBA requires at least 50%- OBC/General and 45% for SC/ST candidate to qualify. Saying about perfect age to study, there is no age bar for study you can learn anything at any age.
Best of Luck for your future.