I always cover mine the day before. We have a cool bedroom that we never use and I set up a table in there and keep the cakes in there where it is cool. I have put one in the fridge before and it was a sticky mess... won't do that again. Just my preferance.
Well, I just left my fondant covered cake in the fridge overnight with royal icing on it and there is no moisture at all! It was not covered, but in a separate fridge by itself. I think the moisture problem may have more to do with the refrigerator type or brand than refrigeration itself. I've always followed the rules and not put it in the fridge, but I think you just have to test out your fridge with a practice cake.
Thanks everyone! I put my cakes with fondant accents in the fridge and the top tier, which I covered in fondant, I left out on the counter. No problems with any of the fondant! Yay! I was so happy with the cake! I posted a picture... it was a 3 tier ladybug cake.
fondant can be put on a cake 3-5 days before if you make your own. I use MMF and it never dries out and it stays in a box on the counter until I'm ready to deliver it. I usually cover my cakes a day early so I can fix any sagging and things the next day when I'm ready to decorate.
People love the MMF and my hair stylist even went 6 days before eating her cake! (Aaahhhhh!!!) She said it tasted wonderful though. :)