For starters, I would have asked this days ago. If you plan on getting up at a reasonably early time tomorrow (or today rather?), I would have baked the cake a few days ago. I'll bake the cake and refrigerate it if I'll be working on it within a day or two, or freeze it if I won't get to it for longer than that. I try to stay away from baking and decorating the same day, just so that I know the cake is fully cool and set after baking. It also gives you more time to focus on the decorating part. It breaks up your time as well, not filling you're *whole* day with cake making/decorating. Bake your cake(s) one day, clean up, get your decorating stuff out and in order, plan what you're going to do for the decoration (although this is usually the first thing that I do before I even start a cake...just because that's how I work), then the next day come with a clean slate, stack and crumb your cake and decorate. I try to stay away from keeping it last minute. If it's the freshness of the cake and not wanting to serve a dry cake, it won't be. Make sure it's well wrapped and you'll be fine. I always double wrap my cake layers on a board with saran wrap and I've never had a problem.
I hope the cake turned out!