Ahhh.....go on. Enjoy it. You got this thing no problem.
For reasons you know...
1. Adrenaline! WOOT! It's a wonderful thing.
2. Spectators, family, friends, other racers encouraging you if you start flagging.
3. No stop signs, lights, 'significant' vehicle traffic on the ride....this will shave time off your "projection".
I know the feeling you have. I'm not far removed from it. While not "Ironman epic", an Olympic still seemed rather daunting to me before I did one. And I too, fixated on the math and calculating...not whether I would complete it...but whether I would make various cutoffs.
I am positive it's one of the appeals of "triathloning" for some of us. We can let our obsessive flag fly. I was chatting about this at a race this weekend with someone....and then she took off her jacket to show me that she'd written out the turns/directions of the bike course on her inner forearm with a Sharpie.
Enjoy the obsessing and even embrace it.....if it doesn't get in the way of enjoyment. Making a list of stuff you need for a race and checking through it 3 times? Heck, the 'beginner website triathlon tips" websites TELL you to do just that. Just when you've double
(or triple
) checked everything. Close that mental door. You checked. You double checked. Your list is complete. Time to race and enjoy it.
Same with the mental math. You've done the math. The math works
(and you know you'll exceed your expectations
). You'll do it no probs. So, you can close the mental door on that one and go on to the next. And if you need reassurance on that.....I say....post away. I'm always up for obsessive threads.