How much prep is fine for pursuing my MBA?

I have the entire set of  Time notes, will that suffice. I will be able to spare 2-2.5 hrs daily from May onwards.

But I am confused on how to start my preparations. My Maths is good but I lack in speed. Vocabulary  needs to be improved.

Please suggest on how to plan my preparations?      Which mocks are good n when exactly should I start mock solving?Any good online course? and is it required or will I be able to manage without it?                                                                                    I have a gap of 4 months in my work-ex.. Will that affect my profile?