What are my chances of getting into IIMs, XLRI, FMS, IIFT with 92% in 10th, 74% in 12th, and a CGPA of 8.2? What percentile should I aim for?

Getting into top B-schools depends on your profile and academic grades as it plays a major role in the marking system in PI. The scores mentioned in the question are good enough and you have a good chance of getting into IIMs, XLRI, FMS, and IIFT.

Moreover, if you are aiming for the top B-schools of the country stop restraining yourself with the thought of what's the minimum percentile. Aim for the full score and try to maximize as much as possible.

Try not to follow the cycle of multiple attempts and increasing a little percentile over the past one just to get in a B-school of your choice. Just Give it one shot but make it your best.

Going by the academics you mentioned, I'd say there's nothing that you can do about it now so stop worrying and focus on your preps. Just give you the best in your attempt and make sure you convert the calls which will eventually land you up in one of the finest top B-schools.