A while back, I wrote up my own race day checklist so that I wouldn’t forget anything on race day; though packing it all the night before is advisable. I found it easiest to organize by event, so that I could visualize what I was doing and what I’d need.
The list in its original form is available on the page accessible from the tabs above, or you can click here: Race Day Checklist. It’s not up-to-date for me since I now wear my Garmin in the water, and sometimes I race without socks, but it should be a good starting resource. I’ve left a few blank lines that you could fill in your own special needs for, and there’s the possibility of downloading a PDF for prettier printing (link at the bottom of the page).
Have a great race!