If you're going to use aerobars, you definitely need to put them on now. If you don't train with them, you can actually be slower than a good position in the drops because the aero advantage is offset by the drop in power.
On race day get a good warm up, see the 40k TT warmup thread.
On the ride, bust it up into 1/3rds, go a little slower in the first third than you think you can hold for the full distance. Second third, if you're still feeling ok, ramp it up to the level you intend to hold for the whole ride. Last third, just gradually increase your effort until there is nothing left.
If you have a heart rate monitor, notice your HR as you do the 2x20's and use that info for pacing in the race.