I wanted to add, I think it also depends on if you are going away to college, or staying home and doing the community college thing. I got Jackson at 18 on my winter break from freshmen year of college but I was still living at home. I had loads of time to work and train a dog... I got him on my winter break so was off for like 4 weeks and had those 4 weeks to spend training, bonding, etc, with him and it was awesome. In certain ways, I think a responsible college student can actually spend MORE time with a dog than a working adult who is married or has kids. Schedules tend to be more flexible and you're young and not tied down to anyone or anything. I wouldn't say that most 18 year olds would be ready for a dog and the commitment that comes with it... but if you are that kind of person, I think it works out fantastic. I'm not one to care about going out and partying much, never lived in a dorm, or have roommates besides my family, and so on... having a dog at this point in my life has been the best decision I ever made. A lot of my close friends went off to college and this gave me an extra responsibility, he's like my best little friend and companion, and also has given me lots of new "dog" friends that I never would have found without having a dog.
But I'm not going to lie and say it doesn't completely turn your life around... you no longer can just go out to dinner after class, you have a living being waiting on you for love, training, food, etc. I plan my class schedule around him so I can leave him at my dads house while I'm away for long periods of time. I can't just go away without second thought. And lots of people simply don't understand WHY... "it's just a dog" is a lot of peoples mindset, or they think your family can just take care of it. But this dog is my life, my responsibility, and to be honest I don't LIKE to leave him, and I ENJOY being with him, and I think some people don't understand that at this age. I'm 21 now, and I think it's really cool to have a dog that is going to go through so many life changes with me... he's already been there through thick and thin for me, and God forbid, let's hope he's around at least another 10 years and I'll be 31. Who knows where my life will take me... but I know he'll be a part of it, whatever that may be.