Gearing up for my first 5K

I "ran" my first 5K back in July. By ran, I mean that I mostly walked a 5K in July. It was quick walking with little spurts of running (which was the plan) and I averaged 13:24 per mile. The goal of the race was simply to finish. I decided to do it with the boyfriend on a whim, simply for something to do. We were both exhausted at the end of it. I finished in 41:32, which put me in 329th (out of 460) place. 

At the time, I'd only recently started running again and my longest runs were a little over a mile. Completing the race was a big success for me.

It's been a few months and I've put a lot more effort into training. Which is why last night I officially signed up to run my first 5K. I'm saying that because I plan to run the whole thing. The Harvest Hustle is a great fundraiser for a camp in the Portland area for adolescents with autism spectrum disorders. I'm happy to support them and super excited to get out there and test myself. It's on October 19th, so I've got exactly 18 days left to prepare. I've got a pretty good training plan in place and am looking forward to actual racing.

To say I am nervous is an understatement. I'm not so much worried about the distance (I know for a fact that I can run that far), but about all the little things. I'm trying not to put too much thought into pace/time and simply get out there and set a baseline for myself that involves running. That said, I should definitely be able to beat the time I set in July :)

Advice for a first-timer?