Weightage of SSC and HSC percentage for admission in IIM Ahmedabad

Hello, I have 88% in SSC and 56% in HSC. I’m starting preparing for CAT 2022 from today (6 months left). Many a coaching institutes said that I should not run for IIM’s as my 12th score is too low. Can anyone help me for this?
Also, I am preparing on self along with Job. I just need good source for counselling and guidance for any doubts. Also, Need help on choosing good Mock test.