I think you'll be fine so far as training goes.
Nutrition, you want to eat partway through the ride. This need not be precise... There will be stations with granola bars and bananas and Gatorade, use them, don't bonk!
Is there anything you've been thinking about re: comfort on the bike? Fit, grips, saddle, padded shorts, padded gloves, pedals, shoes? I don't think you ought to change anything you're happy with.
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Genesis 49:16-17