My FIL bakes his cakes about 1full day before the decorating of them. He lets them cool naturally then brushes a mix of jelly or jam and water over them to seal them, it does not get them wet or show up at all, it's not that heavy. They stay moister this way and it seals them so there are no crumbs in the frosting. Then he either refrigerates them or let's them stay on the counter. I am really not sure about this.
He makes his butter cream right before frosting. It is one of those that is good when it is made up, refrigerating can make it separate and when it's cold the butter will not allow it to be spread easily. Then you have to let it get room temp and re-beat it. So why go through all that. If you are using canned frosting it will not matter, just make sure the frosting is at room temp before starting.
I think if you are going to try your hand at decoration a cake you might want to start practicing now. My FIL, makes all the roses on nails and lets them set up before putting them on the cakes. They always look extra nice and never a glob of frosting dropped accidentally.
I hope you'll post a picture of your cake.
My favorite cake to make from scratch is Hershey's Deep Dark Chocolate with Cool Whip for the frosting sprinkled with pecan halves and colorful M&M's for the occasion. It has to be refrigerated when it's not being cut. The cool whip is cold and refreshing and the M&M's are cold and a bit crunchy along with the pecans it is perfect. Now that I am staying away from tree nuts I just frost it and don't add the pecans.
The cake recipe is light and moist. I think it is because you add boiling water to the mix and then bake it immediately. The chemical reaction starts very quickly and it rises very high.