It is difficult to predict the actual rank or JEE Advance qualifying marks as first time JEE is being conducted twice and rank will be based on NTA percentile score but a score of more than 85 percentile should be a good score to qualify JEE Advance. 

You may calculate your expected rank by given below Formula.

874469 are the number of candidates appeared for the January exam. So rank formula is (100- your total score) * 874469 / 100.

If the number of candidates for April exam increased to 1400000 then your final rank shall be (100- your total score) * 1400000/100

Good Luck!