At 18, expecting someone to know what they want to do for the rest of their lives is a crime. Anyone who says, "Well, your degree won't necessarily contribute to your career choice," clearly isn't footing the bill. If my future daughter came to me explaining that she ultimately wants to be a concert pianist but would like to take her next four years and my next $60,000 to study archeology, I'd flip. While it's common knowledge that you probably won't end up on the career trajectory your academic advisor predicted for you based on your major, you still want to study something where you will gain practical, transferable skills.
I encourage the students I work with to hold off on declaring a major until they feel the time is right, but ideally by the start of sophomore year. Your first semester of your freshman year is going to be ridiculous. For most teenagers, it involves moving away from home, living on your own for the first time ever, rebuilding your entire social life from scratch, studying harder and longer than ever, and experiencing the fun of your school and while avoiding the wrath of your parents. It a crazy balancing act full of completely new things; the least you can do is stop pretending you know what you're doing.
It takes a very smart cookie to own up to not knowing. Young people rush to choose a major to fulfill a college identity, not necessarily because it's what they enjoy. The beauty of admitting that you aren't sure what to study is that people are more willing to help you. Many schools have a University Studies department full of advisors who know everything about every major the university has to offer. Instead of building such a tight relationship with an advisor in a specific field, why not start with a Jack (or Jill) of all trades who you can be honest with about your trepidations and who can help you make a final decision?
It's typical for advisors to map out the course of action for incoming freshman, so even if you have a wide variety of core requirements, there are suggested courses that your particular major feels will best supplement your overall course of study. A Finance major may be encouraged to take Ancient Greek Prose to fulfill a Liberal Arts requirement, but a West African Dance course -- though perfectly acceptable -- may not be as well-advertised. By not declaring, the school is (sorta) your oyster. Your advisor will focus more on fulfilling requirements than following paths, so as long as a course satisfies a Liberal Arts requirement, they don't care whether or not you're reading or dancing your way there. Of course, if Finance makes it mandatory for students to take Ancient Greek Prose as their liberal arts requirement, taking the dance course instead means, if you decide to be a finance major, you'll have to take their requirement later on down the line. It's not the end of the world as long as it's a one- or two-time thing; most majors leave wiggle room for missed opportunities, and summer courses are always an option.
Don't worry about falling behind. Most of the courses you take freshman year are core requirements anyway, so if they don't go towards your future major, they are likely to fulfill a requirement for graduation. What you get from swimming in different ponds is a more well-rounded collage experience. Taking as many different courses as possible better prepares you for the real world. You've used college as both a time to gain valuable skills that can be applied towards future aspirations, as well as to challenge yourself to try things they wouldn't necessarily do. I believe students who enter school being honest with themselves, their parents, and their universities about not knowing leave the school with much more confidence and far less regrets than they counterparts. They experienced all there was, decided on what was right, and graduated with a degree best suited for themselves.