Please help. Pre-race nutrition plan for a 1/2 mary - 12 noon start

Hi,

I am racing in the Toughman 1/2 Ironman distance this weekend in Westcheter NY.
I am part of a relay team and I am doing the run portion only. Problem is I have to be at the race at 6:45 am and I probably won't start my 13.1 mile run till about noon. Any suggestions as to what, when and how many times to eat/drink? I usually wake around 3-4 hrs before a race and have about 600 calories, but I'm a bit perplexed as to what I should do here.

Thank you all for your help