I ate 5 GU tubes (plain, 100cal ea I think) during my first marathon in Portland OR this past October. One about ten minutes before the start, one every 40-45 minutes thereafter. I also ate a ± 400 cal breakfast (granola, soy milk, english muffin with peanut butter, EXACTLY what I ate before my long training runs. By "EXACTLY" I mean I brought all the ingredients from home. It is important to have NO suprises and NOTHING new on race morning) 1 hour before the race and 1/2 a clif bar during, plus some electrolyte gummi bears during as a"reward" at certain milestones. I also WALKED thru every aid station to be sure what I took in went IN me rather than ON me. I took both the water and the carb-replacement offered at every station.
I did this whether I felt "hungry" or not. That's the key, if you wait until you feel like you need it, too late. If you count on having 2,000 kjoules of glycogen available 'cause a text book sez you should you'll probably regret it 'cause everyone is different. With 2 months left you should be experimenting with during-race nutrition to find out what works for you, which product you can tolerate and how much you will need. FWIW I had a good race and did not bonk, but again, I drank and ate BEFORE I felt thirsty or hungry and I experimented during training so I knew what I could tolerate and how much I needed.
Finally, your hydration and nutrition during the 2-3 weeks leading up to race morning is VERY important. Check this out for more info:
http://www.roguerunning.com/articleinfo.asp?id=652
And go ahead and poke around the Rogue website for more info, its awesome, esp. the one about race prep and strategy...
Good luck!