i financed part of my education with a D1 track scholarship, but i am now about your age and 20 pounds heavier, so that is the angle i am coming at this from. We aren't 22 anymore and have to train a bit more carefully.
here are my two cents:
1) It takes a few weeks for the results of most workout to move the needle, so time is of the essence. start with a tempo run today.
2) You need tempo runs and long runs of varying distances, not the same distance every day. i would suggest something along the lines of a one mile tempo on tuesday, a 2 mile tempo on thursday, and a long run of 4-5 miles on sunday. Do some gradual pickups (near sprints that you slowly move into) on saturday in addition to a couple miles. Fill the other days in with recovery runs of 2-3 miles, biking or swimming. just something to get you moving. do this for a month then increase everything slightly for two weeks.
3) two weeks-ish before, the big day, cut back. no need to risk injury. shorten your distances, and replace one of your tempos with pickups.
4) during the last month, losing weight (if you are over weight) will be more important than gaining strength in workouts because that performance will not manifest in time.
5) ice baths are your friend after workouts. Yes, it sucks plopping big oscar and the twins into 40 degree water, but trust me on this one.
6) keep your back and hamstrings stretched and loose. toe touches with weight (i just use the bar) seem to do wonders for me.