Knowing the route is a big help in pacing yourself, so I'd recommend riding or driving a long route in advance to get a feel for where you need to conserve energy and where you can just lay it on if you're feeling strong. It also helps mentally knowing that you're a third of the way, halfway or whatever.

Another tip that might help: adrenaline masks hunger, and I can ride without feeling hunger until I almost literally fall off my bike. Realize that your body does need fuel even though you don't feel hungry, and try to eat regularly - not a lot, just a little. Once my heart rate is above a certain level I have trouble swallowing and digesting food, so I have to either eat very easy stuff, like banana bites, or slow down for a while.

Have fun :-)