How do you store a cake before you frost it?

I am making a three tier fondant cake for the first time tomorrow, and I would like to get as much done tonight so I can take my time assembling and decorating the cake. I am going to make the cakes and fillings tonight and was wondering what the best way would be to store the cake so it doesn't dry out and will still be soft and moist tomorrow. Its going to be 12" 9" 6" the smaller ones im going to zip lock, but the 12" should I put it on a platter and saran rap it? should I put then in the refrigerator?