I'm running a half on May 1st as well. Here's my plan.
The week before: up your intake of carbs. Carbs doesn't necessarily mean breads and pasta- but maybe veggies and fruits. Also, make sure you ramp down properly- you don't need to train full speed that week- give yourself a break.
The night before: have a carby dinner. I think the traditional pasta dinner is fine, fun, and it seems to help.
The morning of: have a breakfast that you know won't upset your stomach. Fruit, yogurt, granola bar, bagel... whatever it is that will get you good fast energy but won't make you sick.
Just before the start of the race- take a goo. Take a goo every 45 minutes you're out there. Find one you like. I like Hammer's Mountain Huckleberry. Tasty.
DRINK the water. DRINK the electrolyte water! I'd avoid the gummies that they might give you- found it hard to chew and run at the same time.
And PACE yourself. You'll be tempted to go out too fast- don't do it.

Go the pace you expected to go.
And GOOD LUCK! You can do it!