Hello,

You need to score the minimum cut off marks specified by NTA to qualify in JEE Main.  The cut off will be declared once the exam is concluded. However, it is predicted that scoring a percentile above 85 will give you decent chances of qualifying JEE main and make you eligible to appear in JEE Advanced. You have not mentioned whether you come under OBC-CL or OBC-NCL. If you belong to OBC-CL then you are considered as general category candidate. In 2019 the cut off for general category to qualify in JEE Main was 89.754 and for OBC-NCL it was 74.3166. According to this if you belong to OBC-NCL you may have decent chances of qualifying in JEE Main but if you belong to OBC-CL then you may not qualify.

However, cut off is subjected to chang, it may increase or decrease depending on number of candidates appeared, number of seats and other factors.

If you are not appearing in JEE Main September session still your percentile is valid and if you have the cut off percentile then you are eligible to appear in JEE Advanced.