First, college is going to be the BEST YEARS of your life -- don't cut it short. Second, a number of younger applicants have hit hurdles in the application process due to young age, and so getting out a year earlier can be disadvantageous. In medicine, you deal with death, disease, grieving families and other heavy emotional stuff. As such, maturity is sought out, and it is generally felt that the fewer years you have been on the planet, the less exposure you will have had to heartbreaking stuff and the more ill equiped you will be to dealing with such. You also need to interact with much older patients, and so having a few extra years under your belt would help with this. And most importantly, this is not a race. You don't want to be perceived rushing toward something without taking the time to figure out what you are rushing towards. Take the time to gain additional exposure, both to medicine and life.