Keep it simple. No need for heart rate crap, no need for power meter crap, none of that crap. What you need is do it the only possible way to do it for real.
I will give you the official HOWZITой™ 20 step training guide:

1. Figure out the stopwatch function on your bike computer or wrist watch.
2. Figure out weather you are fast on flats or climbs.
3. Depending on the answer to step 2, find a 5 mile climb, or 10mile flat stretch
4. Time yourself for the climb or flat... go as hard as you can.
5. Work on 4 week training blocks
6. Start eliminating time off your time trial for the flat or climb, go as hard as you can, and every time shave time off. Do this TT twice a week.
7. After the fourth week, take an easy week.
8. On the sixth and seventh week, do other stuff, sprints, intervals, gym, whatever you want, or work on climbing if you were doing flats, or do flats if you were doing a climb
9. Take another easy week
10. Start again
11. Include long steady weekend rides, about 4 hours minimum.
12. Keep taking time off your course. Set goals. Remember, you will only get better if you progressively do your Time Trial harder
13. Eat good, sleep good, drink a lot.
14. Make sure you have a daily stretch routine.
15. Maintain your bike and equipment
16. Meditate whenever you can.
17. Stay away from crap like heart rates, power meters, VO2Max e.t.c
18. Persevere
19. Succeed
20. Live the life you have imagined