Insert a knife or toothpick in the center of the pumpkin pie, and if it comes out clean, it is done. Hope that helps!
This is what I do, I put a butter knife edge in the middle of the pumpkin pie and if it comes out totally clean I know it's done (they I just cover that spot with decorative whipped cream. . .like a leaf or something)
I do the knife insert using the time guideline and if my knife comes out just shy of clean I pull them out and let set, they finish cooking with out over cooking that way. I'd say after an hour, it's more than likely over done, but as long as it's not burned should still be edible.