Try a longer warm up, starting easy and building to some race type efforts. Throw in a couple of real vomit inducers just so's your body knows what's coming up.
Are you eating correctly pre-race? Nothing later than 2 hours before and keep it light. Serious eating (the big pasta etc.) is for the day before the race. An energy gel just after warm up is finished and water to be properly hydrated.
Longish warm up, starting easy with a session at race speed about 5 minutes from the end, then taper off and try to arrive at the start only thre to five minutes before your allocated time. You MUST stretch before starting warm up, gently while you are waiting to start, get some deep breaths for the starting effort, and stretch before and after EVERY training session and race. This will do more to prevent cramps and injuries than all the pills in the world.
This way you should be able to start fast and keep it going, remember in a TT if it's not hurting it's not fast enough. The degree of hurt is up to you, but the object is to finish feeling you have nothing left to give.
Then go for a gentle warm down for at least ten minutes, do the stretches, THEN check to see if your time has been posted.
Following that a recovery drink, some high energy food, and you'll be set up again.