There are a bunch of great athletes in this group, and then I suspect there are a also a bunch of middle-to-back-of-the-packers like myself. For some of us doing our first Ironman, success isn't guaranteed. There's no doubt in my mind that all of us are capable of finishing the race in under 17 hours, but some of us may be more vulnerable if we have an off day. And anything can happen along the course.
My question is, and I don't know if people have answers for it, at what point do you think you'll be confident that "yes, I'm going to make it." Or if you've already done an IM, when did you cross that threshold? I used to think that as long as I could start the run I would be OK. The bike cut-off is 5:30, so in the worst-case scenario I'd just have to do a 6.5 hour marathon. That sounds kind of easy, but then again at Wildflower (an admittedly much more difficult run) I did a 3-hour half-marathon. So a 6 hour marathon isn't too unrealistic, and that could be cutting it close.
I think that if I can reach the half-way point of the run by 8:00 then it's pretty much in the bag. I'd like to be well ahead of that, but with 4 hours to do 13 miles I don't think I'll have to worry about finishing.
What about you? Do you have a mid-race goal that will signify "yes, I'm going to finish this thing!" ?