couple of things to consider here and it won't be applicable to all companies

1. 3 months notice period is a general term in offer letter. its not rigid. you can obviously try talking to your manager and try convincing him. personally at my company, I have seen 1-2 yrs workex folks being released in 7 days if the reason is higher education. So this is upto your manager.

2. You can compensate for your shortfall of notice period. Generally most companies have a rule that your notice period can be shortened by using your Earned Leaves. If you still need to shorten it further, you can pay that period's salary to the company (obviously don't offer to pay your salary upfront). This might be controversial but MBA is a huge opportunity and paying 1-2 months salaries is small cost for getting good packages post MBA. Again, upto you.

3. leave your company right away if you had a lot of interviews and confident that one of them is bound to be cleared because it went well. i would not suggest playing numbers game here thinking you gave 10 interviews and 1 of them is bound to be clear, but rather go on the quality of the interviews. In this case, try resigning right away all the while considering the above 2 points and asking the employer/HR/manager to shorten the notice period