For this particular cake, both the flowers and the cake can be mad quite far in advanc, which removes a lot of stress from the weddng week itself. Like all traditional fruit cakes the cake is made in advanced and soaked in small amounts of liquor ( I used brandy) over a few weeks or months. This will be familiar to anyone who has made a christmas cake.
You should use a recipe specifically designed to be a wedding cake as it will ensure that it is sturdy enough and that it makes the right amount of batter and icing. For a three-tier cake, you need to make three cakes of 12", 9" and 6", as well as a massive amount of icing. Most three-tier cake recipes have a step-by-step schedule for when you will need to bake and assemble each part.