Do both intervals and long runs. Intervals do at goal pace, I'd suggest 800's or, better, miles.
The long run, I would do this week or next, but since you only have a month, I would only do one. Go for 8+. Seriously, it will help tremendously.
EDIT: I was thinking the test was a 3 mile, not 2. In that case, scale back the long run to about 6-8.
Like someon has said, 5-6 times a week is good.
Taper off as you get close, no hard workouts the week of. Something short and fast, like 200's slightly faster than goal pace.
As someone said, you didn't leave yourself much time. Try to get as much mileage as you can this next week and half, and then taper down.