Going in the military? Make sure your heart is okay by your doctor first.
First stop running 2 miles. Save that for all out time trials to check your progress. Don't do all your running on a treadmill. Treadmills are great but you need actual road time too. Running for cardio unlike lifting has to be done frequently. Run 5 to 6 times a week. Shoot for 3 to 5 miles a day. If you have to work up to that keep at it. The world will keep spinning if you run a day or two on a shorter run than your goal of 3 to 5 miles a day. Time your runs. Not for the goal of beating your time every training day but to record progress as it happens. Establish different but repeatable running routes. What I mean by that say the park could be a 3.5 miles loop. Your neighborhood your 5 mile out and back. Just so you know when you time it you can compare. The goal isn't to beat your time every run. It's just for reference. If you make it your goal to beat your training run every time your training will be become so hellish you will start missing days and give up. Don't be concerned. Run hard and the times will soon drop. Consistency is the key to improving cardio.
So the plan is to shoot for 5 to 6 days a week. The world won't stop turning if because of unforeseen circumstances you get 4 for a week. Run 3 to 5 miles a day. It will make 2 miles seem like a very short run. One of your 5 to 6 cardio training days use intervals. Intervals make for quick progress but the injury potential and burn out factor is there so keep it at the most one to two days out of your cardio training week. For improving your two mile I would recommend 6 x 880 yards (half mile or 800 meters. It's two laps on a track or two on a treadmill lap indicator). Your rest in between each half mile run will be fast walking/ super slow jogging one lap (440 yards/400meters or one lap) You can do these at the local high school track or on a treadmill. These can get brutal but wow do they improve your distance running time. So it's 6 sets of a half mile. Warm up with a really slow mile. Don't forget to cool down letting your heart rate come down by walking when your are finished. I would suggest the first half mile interval is your slowest and build a little on each one. Your last should take you to the absolute limit.
What you're doing to improve your 2 mile run is not productive. Getting on a treadmill every day trying to beat yesterday's time for your two mile run will result in burn out and even possibly slower times. Might work for the severely out of shape for awhile. Think of it in bodybuilding terms. Many say add 5lbs to exercises every week and take every set to failure. If we could keep doing this we would be all benching 1500lbs after awhile. LOL. Again consistency is the key.
To answer your question is it possible to get your 2 mile down from 18 to 16 by June? Yes, very achievable in a healthy young man. Even an old goat like me. My son was running 16 minutes in the two mile when he was tested by the Army Recruiters prior to getting in. Once in his time dropped to 14 minutes. I know with more consistent training he will be laughing at 14 minutes soon. For a soldier or a fighter having gas in the tank is so important. Anyone that has boxed or submission wrestled knows being strong is meaningless if your run out of gas. That's why all boxers, wrestlers and MMA guys put in the road time. If you just care about cosmetics then it's not important.
