Firstly NTA will published jee main paper 1 percentile score. Previous year cut off for qualifying jee main are 74 %marks for general, obc 49 %marks and SC 25 % marks and ST 24%marksyou Crosses these percentile marks you have chance to sit in another level i. e jee advance. Going for 2019 cutoff for jee mains exam. Gen (67to 70 )%marks, for Obc( 37_41 )%marks, for sc (23  to 25)% and for st (20 to 23). These are cutoff of current year marks should Abe to qualify and chance to sit in jee advance exam.

Hope my answers will help u. 

Hello!Siddhant

Cuttoff Percentile of jee  mains are going to expect around 85 under general category.70 percentile would be enough for SC category candidate to be elligible for JEE ADVANCE 2019.For sureity wait till NTA decalres cuttoff for each category candidates.

GOOD LUCK!