You should in most cases order the cake six months before the wedding, it's best to start considering what you would like soon after you've chosen your venue. It may help to look at images and books or online for for cakes that fit your buget and taste. Think about the look and the flavor you desire to help narrow your focus. Consider a flavor your guests will enjoy as well as you and your groom. Or maybe you love strawberry filling. These ideas you find may help you come up with creative ways to incorporate your favorites so they fit your wedding.
The cake's design should match the aesthetic of the day. A formal wedding generally calls for a structured, multitier cake; it can be elaborately or simply decorated, so long as its style implies something ceremonial and grand. These cakes are often round, but square or even hexagonal shapes are more unexpected -- and the tiers can be stacked for a solid look or set on pillars for an airy grace. White is the classic color for a wedding cake, but chocolate and tinted frostings can be just as elegant. For a less formal wedding, you can certainly embrace the unconventional. The cake can be iced playfully with swirls of meringue or strewn with flower petals that fall where they may.