I was wondering how far in advance can you make a cake?
Are you referring just to the baking part? If so you can make it well in advance and then freeze it (I usually wrap in a couple layers of saran wrap and then heavy duty foil).
I do the same when required, I can make them well in advance, freeze them, cover them and they are good to go. I find that when I cover the cakes whilst they are still half frozen, they are unbelievably moist. Having said that, we don't layer the cakes in Australia as much as you guys do, I am talking about solid cakes, mud cakes etc.
I also do the same when covering them, 3 layers of glad wrap and then foil.
From laying the fondant to finish decorating, I'd only go for a maximum of 2 days.