Hello Diptajit, Yes you are eligible for the second stage. As per guidelines given by AIMA a candidate is graduated from a recognized university or institution. NRIs and foriegn students are also eligible for this examination. There is not any minimum marks or cgpa or agreegate criteria for this examination however some institutes fixes the minimum number of marks or agreegate in graduation you can avoid those institutes. This year the MAT pen paper examination will be held on May5, 2019. A candiadte sholud be passed or appeared in their graduation examination. This examination takes no age bar or maximum numbers of attempt. A candidate can give this exam with miximum number of time. MAT examination is a gateway of many B schools in India. More thsn 600 B schools accepts the score of MAT examination. The Fees of those schools are considerably very low. This examination is conducted Four time a year- february, May, September and December. As you mentioned above you got 81.73% you can apply for many colleges in India which has very low fees and high placement. You can apply individually on those institutes.

hope this will helps you

all the very best