Thanks for sharing your profile. It's always great to start thinking about b-school early so kudos to you. You are already on the right path with a great GPA and undergrad academic performance. You're chosen career path is a natural feeder for MBA programs so you will be on the radar of MBA programs when you choose to apply. Now you are applying to some of the best schools in the world so you must realize grades and pedigree alone will not net you an "admit". I would focus initially on performing as well as possible in your job which is the most important first step. B-schools want the best of the best so by showcasing you are a top performer you will help strengthen your candidacy. Also, many bankers apply to b-school so performing well at work is not always enough, start engaging in activities outside of work particularly in leadership roles to help stand out in a crowded field of homogenous bankers.
Finally I would recommend taking your GMAT as close to graduation as possible while you're already in studying/academic mode to maximize your chances at a high score.
Hope this helps!