Don't be discouraged by family! That alone should be your motivation! You can do it. When I first started decorating I used American Buttercream. It was Sharon Zambito's recipe and it is a crusting buttercream. I watched a ton of Youtube videos and learned quite a bit from them.
Whether you bake the day of, or the night before, all depends on the amount of detail you add to the cake. I always bake my cakes the day before so they can set. If it's a very detailed cake I bake a couple of days before and give myself time to decorate.
If you are going to use a fruit filling you may have to refrigerate, depending on whether you purchase the filling or make it yourself. Have you decided on what you'll fill your cakes with? I'm excited for you!! Good luck with it all!