How far in advance can I make cupcakes for a bake sale?

If it was me Wed would be pushing it if you don't have freezer space.  Or you could do what you  do have freezer room early and the rest closer to Sat.  6 dozen is only 3 batches of batter, 3 times in the oven if you have (or can borrow) 2 pans that each hold 12.  So that really isn't that much time, either do single batches or do a large batch and let it sit while the first two dozen are baking.  Are you going to do a simple swirl design?  That will go pretty quick also if you have the icing all made up ahead of time.  Get that done right away so that is one thing done with.  If I was doing 4 or 6 dozen I would put them all in my transportation containers ( do you have some short plastic tubs you could use?) then do the swirls while they were in the container and load in the car and done.  Otherwise I would bake Th and ice Friday for the Sat sale.  A lot of people say the fridge (a regular house type) will dry out cakes so I think you are better to freeze or leave on counter, not in fridge.

I'd do them Friday. If you're nervous about time make your icing and load your icing bag ahead of time and have all of your liners separated and ready to go. Buy/borrow some extra pans so you can be filling while others are baking. It takes me about 1 1/2 hours to make, bake, cool and ice 6 dozen cupcakes, but I have more than one mixer and two mixing bowls for each. If you do them ahead store in a bakery box or turn a cardboard box upside down over the cupcakes on your counter or table. If you put them in airtight containers the liners will separate from the cupcakes.