B-schools won't care about High School. As for your acheivement, it would be worth noting to the extent you have leveraged finishing college early to achieve something interesting professionally. In other words, if you were able to springboard as a young alumnus into an early leadership role at work, becoming perhaps the "youngest" at your company to achieve x or y, then that would definitely help. This brings me to an interesting tip when impressing adcoms: consistency. Adcoms like to see trends in your acheivements, a demonstrated history, if you will, of traits and accomplishments. This is why it's always good to be involved in activities outside of work over time that are related to a common passion or theme. This demonstrates maturity, focus and vision, all of which are attractive to b-schools and attributes they like to see in their candidates. hope this helps. BTW, your GPA is good--definitely at, close to, or above average for b-school, so no worries there.
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Bryant Michaels
Admissions Consultant