Hi ANS396,
With experience of 9+ years, a score of 670 and above will get you into contention, so aim for at least that. Of course, the higher you go the better, and crossing the 700 mark will only add more certainty. Keep in mind, though, that you will be among the few people applying to ISB with that much experience, so expressing in your essays your future career plans and how ISB can help will also be very important for you. Anyway, for now, focus on the GMAT first. All the best!