TTs are about focus and self monitoring. You don't need to ride the full distance, but enough to get a feel for what you can maintain. 2 minute intervals would have a place in a long term program, but are too short to let you dial in a steady state effort. Try 6' repeats. First one all out. Back off on the rest a little. On race equipment so you get the correct level of feedback.
You don't want to start out in the red; you won't recover if you go too far anerobic. Feel like you are holding back a little for the first mile or so.
jdott is saying similar things.