Understanding the Premed Track
So what does BEING premed mean?
Being premed means you want to go to medical school. It means you can major in ANYTHING you want as long as you take certain premed classes to prepare you for the MCATs and medical school. If you want to pursue any of the other health professions (vet, dental, physical therapy, nursing) then you will take basically the same classes with a few exceptions based on the graduate school requirements.
Major in whatever you LOVE. Medical schools do not have a preference for one major over the other so please be true to yourself and your talents.
Some medical schools will indicate a specific list of exact courses a student must complete before matriculating into medical school. While many other medical schools have distanced themselves from a prescribed list of prerequisites instead favoring a more inclusive common set of competencies that emphasize the holistic review of applicants. University of Michigan is a great example of this approach. You will need to balance both types of medical schools and carve your own path of prerequisites for medical school taking into account both approaches.
You may want to read a few medical school websites to see the variety of requirements required (science and non-science) and see what language they use to describe those requirements (recommended, required, strongly suggested). Select a variety of state and private schools to research. Start making a spreadsheet of prerequisites, recommended coursework and noteworthy qualities you find out about each medical school you research. This information will help shape your eventual list of medical schools but it will also help you learn about summer research and clinical opportunities that might interest you along the way.
At the end of the day, in order to get into medical school, you want to establish a solid academic foundation, ground your interest in helping people and medicine through internships, volunteer and research endeavors and feel well prepared to take the MCATS. Since you will be applying to 15+/- schools you might want to be more conservative in the actual courses you will take to make sure you cover all of your bases. For example, testing out of the first semester of General Chemistry might seem fine for now, but what about the labs? What if some of your medical schools require 4 Chemistry labs? You may have to plan on taking an upper level Chemistry lab later on (such as Biochemistry) or take just the General Chemistry lab but not the lecture. This does not have to be addressed right away, but it should be in the back of your mind and on your list of questions for your premed advisor. If your 'dream' medical school requires it, you will have to address this before applying.
Remember, you have 3-5 years to take all of the classes you need so don't feel overwhelmed as a freshman. Focus first on the classes you need to prepare for the MCATs. Taking biochemistry as a senior is perfectly fine. There will be plenty of time to fit everything in even if you change your mind and change your major, drop a class or want to study abroad.
Be flexible as to 'when' you plan to apply. In 'your' ideal world, you may 'want' to apply after your junior year, but in reality you might be a stronger applicant if you waited until after senior year. Be flexible with your timing and realistic about your competitiveness. The goal is to apply once and get in; not apply and see how it goes. Get honest feedback on the strength of your application before applying. Remember, the average age of medical school matriculants is 24, so many students take time off before going to medical school. Medical schools appreciate the more mature applicant so take this into consideration when thinking about your application timing.