I used the homemade pectin to make some jalapeno-peach jam late this afternoon. The jars are still warm, but there was a little extra, which I put into a small jar and then into the fridge.
*It looks like it worked!*
It's not a hard set, but jam isn't supposed to be. I still have enough pectin for another batch, so maybe I'll try a jelly with that. But right now, I'm thinking it really did work! But like the title says, we'll know in the morning. :)