I don’t know a whole lot about cycling, but I don’t see a problem at all using it the entire time.
But, if you’re looking to use it just for a specific phase, then I’d go with the shock part - as this sounds more demanding on your body. You’d be able to keep your natural test levels up, through the stressful time when they’d normally drop.
I really think you’d be happy using it the entire time - really add a boost to your training.
It probably wouldn’t be a bad idea to even take a dose just prior to your race.
You’ve hit something with your idea of overcompensation - this would be when your body converts ‘excess’ testosterone into estrogen. I say excess because the ‘normal’ amount varies from person to person. You could help optimize your hormonal profile by adding M (an anti-estrogen) alongside the TRIBEX. Or going with Alpha Male from T-Nation.
Hope this gives you some helpful insight and good luck with your race!