Can I poke my baked potatoes the night before and store them at room temperature overnight?

I wouldn’t recommend doing that. Your pokes will expose the potatoes to oxygen and the potatoes will turn black wherever the fork tines pierced the skins. It is very infrequent that a potato will burst from baking if you put it in the oven when you first turn it on so that it has a chance to come to temperature. The potato will take about one hour at 400 degrees F and is considered done when its internal temperature reaches 210 degrees. You can usually smell the potato when it is nearly finished baking.