Think about it this way- You should do a gap analysis and understand where is it that you want to be in life in 3 to 4 years from now.
I mean- If you see yourself working at a product manager in Google, Amazon etc, then may be you should raise questions such as- How to get to Berkeley Haas, or UCLA or Stanford( most of these programs have around 5 years of average work experience). Or if you see yourself working as an Investment banker in New York, then definitely Stern or Columbia or Wharton( All of them will need GMAT).
If you think you want to work in Mumbai in one of the Fortune 500 companies, then ISB will give you a great access to these organisations as ISB is the LOCAL MBA God of India. ( if you are keen on financial aid in the Global programs – also read- What GMAT score do I need to get a full scholarship? I am an International Student)
SO, do not – and I suggest- do not spend time taking tests and staying busy. Rather- find out where is it that you want to be in your life and then Find your way forward.
And hey- IIM A and IIM B are great programs. But if you have 4.5 years of work experience already, you will have completed 6 years by the time you join them. i.e. YOu may not find IIM A or IIM B ( through CAT) a great match given your current seniority as compared with your peers.