Cake Keeps Refrigerated for Seven Days
If properly refrigerated, the cake itself as well as buttercream and cream cheese frosting will keep for up to seven days. Any cake can be baked a week in advance, and if using one of these types of frosting, it can be frosted and decorated as well, so long as it is kept refrigerated between 30 and 45 degrees F.
Fondant Should Never be Refrigerated
If you plan to decorate your cake with fondant icing—a thick sugar paste—decorate the cake within a day or two of the wedding. Homemade fondant has a shelf life of about three days unrefrigerated. If you refrigerate or freeze fondant, it will crack and be ruined.
Bottom Line
It is always safe to bake the cake up to a week in advance and refrigerate it in the meantime. However, how far in advance you can decorate the cake depends on what type of frosting or icing you plan to use.