I am making a large sheet cake for a friend's graduation in a few weeks.  The party is on Saturday, however I am leaving for vacation the prior Thursday.  I am planning on baking/decorating the cake Wednesday and delivering it Wednesday as well.  However, I don't know if I should have my friend freeze the cake to keep it fresh until Saturday or just keep it covered in plastic wrap?   Also, I wanted to put edible pictures on it, but I hear the edible pictures don't...