How many days in advance can you safely wash, then wrap potatoes in aluminum foil for an upcoming event?

If you can let the potatoes air dry after washing, then wrap and refrigerate they should last up to a week. Don’t poke the potatoes with a fork to let steam escape. Where you pierce the skin the inside will turn black when next to the aluminum foil for an extended amount of time. Unless doing potatoes on the grill or on the coals of a fire, I usually recommend not wrapping in foil. Here are some tips from previous posts:

https://idahopotato.com/dr-potato/can-i-wash-and-wrap-potatoes-in-foil-three-days-before-i-bake-them

https://idahopotato.com/dr-potato/why-i-do-not-recommend-baking-potatoes-in-aluminum-foil

https://idahopotato.com/dr-potato/foil-baked-potatoes

https://idahopotato.com/dr-potato/how-do-you-bake-large-quantities-of-baked-potatoes