I'd try to not think about the competition and just think about me at home practicing. But, who am I trying to fool? Even at home, when I start to feel that the solve is gonna be a good one I start to get nervous, my hands get sloppy and I usually spoil the solve with a PLL error, etc.
But look at it this way: you are not in a position to win the comp, right? (judging for your 26.53 on the signature) so, why bother to get nervous? Just enjoy the experience, do the best you can, try to be relaxed and make friends! I'm also thinking of going to my 1st comp either this fall or next year and I'm sure I will be nowhere near my PBs of 17-19sec but, whatever! You will also start appearing in WCA official listings, which is cool ;-), even if your official PB is a 28.xx sec solve.