It's very hard to map out the rest of your life when you're only 16 years old. I don't recommend being pre-law in undergrad. A political science degree is not a prerequisite in applying to law school. In addition to poli-sci, English majors, engineers, graphic designers and business majors also apply and get into law school.
Your major isn't important. How you perform (your GPA and LSAT) are critical to getting into law school.
At this point, I suggest you survey a number of careers that are of interest to you. Talk to students studying these areas who are in college. Sit in on a class at the local college. Also, take the time to find practicing attorneys and graphic designers. Ask them about what they do and see if you can shadow them for a day.
It's a GREAT idea to major in something not law-related and work in that field for a few years. It will you give you great perspective, and you'll have something unique about your application that the scores of poli-sci majors don't. You may also decide you don't want to be a lawyer, which is fine, too.
There's nothing wrong with being a poli-sci major, though. Nor an English major. Or Economics, etc. Major in the areas that you think are interesting. Take advantage of career testing to see what your strengths are. And then talk to people in those fields. It isn't uncommon to switch careers (not just jobs!) multiple times in one's life, so don't feel like you have to stick with something you thought of when you were younger. The person you are at 30 will be very different than the person you were at 18! It's ok to change the "plan."
Don't worry about not having it all figured out at this point. Just do the best you can and get great grades -- so that you can get into college. Once you are there, take the classes that interest you-- even if they are things you never thought of before. One of my classmates was an anthropologist before coming to law school! We really take all kinds of people from all kinds of backgrounds.
Good luck! Take your time and do your research.