I recommend you take a longer-term approach, given that you've been on the shelf for the past few months. Unfortunately, it's going to take more than three short months to whip yourself into the best shape of your life.
Focus instead on securing a roster slot for the beginning of your sophomore year. If you give yourself more time to work with, you will be able to reach a higher level of fitness in a more sustainable fashion.
The revised timeline would look something like this:
Fall: Build up to full volume
Winter: Perform strength-based workouts; jump into a road race or two
Spring: Continue with the above, but add speed-based workouts
Late-Spring/Early Summer: Run your target times; lobby the coach for a roster slot on the Cross Country team
Keep things simple. In the Fall, just run mileage at a relaxed pace, with strides 3-4 times/week. Double as many days as possible. Increase the length of your long run each week.
In the Winter, do one tempo/progression run and one long interval session (e.g. 6-8 x 800m) a week. Maintain the long run.
In the Spring, do one strength workout (tempo run or long interval session) and one speed workout (e.g. 24 x 200m; 12 x 400m) a week. Keep doing your long run, but reduce its length slightly and pick up the pace accordingly. Reduce your weekly volume a bit when it comes time to race on the track.
The point of all this is to 1) Maximize your chances of running the time standards you listed, and 2) Maximize your fitness, so that you can actually contribute to the team once you earn a roster slot.