Dear Student,
Glad to hear that you aim to be a Management Consultant in future. Though the main study for it starts after your class 12th that is in graduation before that what subject you study doesn't really matters but if you want to have a prior knowledge in that stream only you might go for commerce or maths as per your preference and interest or Commerce with Maths if possible as a subject or stream in your 12th. A lot to experience is ahead of you.
Hope this might help you.