Personally, I'd try to set my affairs in order as much as possible, then once the pain got to be too much, I'd put a pistol in my mouth. I'm not going to eat my fellow man, I want them to have a chance, and I'm not going to sit there and suffer, because there won't be some miraculous cure that pops up 30 seconds after I get bit.
Edit: And as long as I'm still well enough to do so, I'm going to take as many ******** zombies as I can with me.