You can bake your cakes, and wrapped with cling film and tin foil, can be frozen up to a month before using. Do it all the time. A frozen and thawed cake is much moister than a refrigerated cake. Refridgeraing your cake without icing dries it out. You can crumb coat your cake, wrap then pop in the fridge or freezer. Or after crumb coating, pop in the fridge for 30-40 min until hard, and ganache right away if you wish. Although, I like to have my cakes settle over night. Removes any air bubbles, and any bulges that occur can be fixed next day. I sometimes lay a light book on top with wax paper underneath to weigh the cake down. No need to refrigerate after you ganache is set. Ganached cakes can sit at room temp for up to 3 days. So you can add your fondant after your ganache is set, or a day or two after. I would use royal icing for your dam. Sets hard and your filling won’t leak.
Hope this helps.
Creativity is God's gift to us. Using our creativity is our gift back to God. Clarky's Cakes 😎
