If I'm brining for two days should I add butter with brine or ontop the day of?

Day of. The recipe doesn't call for brining, but air dries the turkey in the refrigerator instead. I assume you're brining then using the herbs and baking methods from the recipe. Butter in the bring won't really do anything but harden like a stick of butter, so just rub it on prior to baking the way the recipe directs. Good luck! I hope it's delicious.