I have to agree with Dustin. The idea of a fulcrum implies that there will be movement within the handle. There should be none at all since you are using epoxy, thus once the pin is in place, it's location is cosmetic. I also agree that if I were to use a single pin, I would locate it slightly forward of halfway. Even so, this takes planning to make sure your tang is long enough especially if you are intending on using spacers. If this is a small to medium sized knife, you should be fine. Good question.
This is your first knife, right? That's good. I'll be the first to encourage you to keep it up and be sure to show us your work.
Here is something to think about. If this method of handle construction was in question in YOUR mind, why not build it with another method that you're more confident of? I look forward to seeing it. Lin