I want to go to medical school where do i start?

i am 21 years old, female, and i live in MA. ive decided i want to go to med school to be a cardiac surgeon but i dont really know where to start. i graduated from high school in 08' i went to a vocational school and my "shop" was health careers, where i become a certified nursing istant also. i am currently at lincoln tech to become a medical istant and i graduate in july. i need to graduate first, get a car of my own, and start working before i go to school, but is there anyway i can look into schools now and should i apply to a school now? i know i have to take the pre- reqs and all that, but what school can i go for that? can i take the pre- reqs at the med school i want to go to, which is either tufts university or um? idk if i should at least go talk to a college and get my foot in the door and learn about the program too. help please. and also, how much does a state school like um and tufts cost each year?