R.W.
Personally I would bake the cake and put it in the freezer until the day of the party. Wrap it up tight or put in air tight plastic container. Wait and frost it the night before or the morning of the party. It will turn out a lot better. You don't say if you are making homemade frosting or using a can. That also makes a difference....If I were you I would experment ahead of time seeing it's your first cake. Good Luck and Have Fun!!!!!