Hello dear student,

that is good percentile and you being student with reserved category there is a chance that you might get admission in NIT. And there is a probability that you are eligible to give JEE advanced also as your percentile is above 85. And roughly the students having percentile above 85 eligible to give JEE advanced. You can expect your rank in between 99,700-99,800

If in case you do not get admission in NIT then also you can get admission in good government colleges who consider the marks of JEE mains.

If you want to calculate your rank by your own then dear student you can do it as total percentile score is the percentage  of people ahead of you. 869010 are the number of candidates appeared for Jan exam. So rank formula is (100 - your total score) X 869010 /100.

If the number of candidates for April exam increased to 1200000 then your final rank shall be (100 - your total score) X 1200000/100

Best wishes