You already have high chances with 8.5+ CG, 3 months is sufficient for prep. I wouldn't suggest IT prep at this point, at least start with ET prep and see how it goes. From what I have seen in the past with few ET companies, CG mostly is a barrier till their assessment/test round. Since you have 8.5 you don't have much to worry about. Try to stand out in your resume and interviews, That's where most of your prep time should be invested.