Dear applicant although JEE Mains is conducted in different phases and the cut off depends upon the number of students who appeared in the exam, the difficulty level of the exam and the seat matrix of different colleges. But as a reference based on past few years, the cut off score for SC Category students remains around 46 ( minimum) to 86. Yes it can again vary based on the situation and for JEE Advanced too, same case is applicable and your score has to be around 55%.

Hope it helps!!!