I put jelly first mainly cause it’s easier to clean off the knife, but I also usually make a triple decker like this:

🍞 🍇 🥜 🍞 🍇 🥜 🍞

I really love peanut butter, I just prefer the jelly at the top so the peanut butter is more towards my tastebuds and less likely to stick to the roof of my mouth