Bake them a week ahead of time and wrap them well (after COMPLETE cooling) in plastic wrap and then in Al foil. Freeze them until the day you want to ice them. Remove them from the freezer and allow them to thaw while still completely wrapped up. I find that this actually enhances the moistness of the cake.
But if you are at all concerned about the moistness, a very very easy way to ensure moist cakes is to brush each layer with a cake syrup as you assemble the cake. Cake syrup is 1/2 c sugar: 1/4 c water. Bring to a boil to dissolve the sugar and allow to cool to room temp. You can add flavoring to it or not. Lemon or vanilla extracts go nicely with plain cake. Raspberry liqueur, grand marnier (orange liqueur), peppermint extract all work nicely with chocolate cake, depending on the filling and frosting flavor. Kahlua is nice if you're looking for a coffee flavor. More info than you asked for, but I got going!! 
Hope this helps!
I defrost them on the counter. Good to do it on a cooling rack so they're not sitting flat on the counter. I leave several hours before I want to frost them, so if you're going to do it in the morning, take them out before bed the night before.
Caution: I did this a couple of weeks ago and our dog helped himself to the 8" tier -- the WHOLE thing -- as we slept! 
Yes, you can bake them ahead of time and freeze them. I neer leave my cakes frozen more than 1 week, but I am sure it can at least last 2 weeks. Here are my 2 cents:
To freeze:
I bake my cakes, let it cool, tort them. Wrap them in foil paper then with plastic. Freeze.
To thaw:
Remove from freezer and let it thaw wrapped. Unwrap, let it thaw more. You are ready to go!!
I find that cakes are more moist with this method and they taste the same or better as just out of the oven.
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