Go for it. Unless you start at a _very_ young age (like 4-10 years old), you won't get much benefit from your young age. Actually I think it's easier to learn instruments during or after teenage years, but as the age grows, people have less and less patience to spend years practicing the basics of their instrument. The semi-advanced music theory is something you can learn in matter of months, if you practice it daily, and that will be far above the knowledge level needed for playing ie. bass or basic rhythm guitar. You'll learn while you play, it's a fact.
Learning an instrument is most about motivation. If you can practice daily, you will progress well. With playing guitar for 30-60 minutes per day, you will learn the basics in 1-2 years, and after 5 years you are able to play quite challenging pieces. The speed of learning depends on practice time and on how many styles you wish to learn. If you concentrate only in ie. classical guitar, jazz guitar or rock guitar, you will learn it faster, but stay pretty green on another areas, heh. Quite much like me. I can metal guitar pretty well, but have trouble plucking fur elise on a classical guitar, hehe.
Keep in mind that electric guitar or bass do not require starting with an acoustic, if you don't wish to do so. Usually people start with acoustic guitar just because it's cheaper to get. Bass has the lowest learning curve, so it could be a good idea to start with it.
I think I'd enjoy it but I can already "feal" my creativity fading in other things I do.
