HardLoper wrote:
I would recommend a lot more speed and don't wait until December to start. I would start with once a week hill sprints on a short uphill 8-12 seconds. Do a 6-10 x uphill relaxed all-out (95%+) with long rests - 2+ minute jog. You should feel sharper and more powerful almost immediately. Eventually you can transition to faster speedwork on the track with spikes on which will take more out of you.
(I just read the post above me and he suggested basically the same thing.)
Agreed, 100%.
Don't think of speedwork in terms of "sharpening" or anaerobic capacity work. Think of it in terms of "pure speed." It's neurological training, and it's crucial for the mile. You'd be best off doing a lot of what HardLoper suggested, combined with a moderate tempo every week.