When you leave highschool you will be at the appropriate age to attend college with your peers. Waiting will make you different, not better among them. Thirty years ago no bachelors was no biggy. Today no bachelors is a recipe for janitorial work (which you will do in every branch I guarantee). Go get your bachelors. Personally, I wouldn’t worry about the military. But, if it’s what you want then do as I’ve already told you.
BTW let me give you some unrelated pointers to put you ahead of the curve. Find out where you stand about God. If you find that is something that matters; then figure out what you think the right thing to do is with some incling towards that.
Make your word count. Stop wasting time, its about to start moving fast. Look around you, the people you know are unaware of their direction, get out in front and beat them to the finish. 4.0’s are not that important. 3.0’s are borderline moronic. Don’t let another word come out of your mouth that you haven’t weighed twice, and if you can influence someone with it do it. Don’t do anything that you haven’t thought about twice. My brother was locked up for the rest of his life by 17. You are heading into interesting times, brother. Keep your mind clear, and ready. Others will act irrationally, wait for this and when they do learn from it, and if you can do it without hurting them more than they already hurt themselves, gain from it.
Go to school and get as many degrees as you can stand before you know what you want. Learn everything you can, and learn how to do everything you can do yourself. The military will give you discipline and a stiff upper lip. There is no substitute for infantry basic training. These things can be gotten from hard work in a sport on a different but similar level. If you haven’t mastered anything then do. There’s lots of advice, find it.