I am making a wedding cake for a close family friend who was asked to make her niece a cake (she feels way to under pressure to do it so has asked me to). The wedding is on Sunday but they are leaving Friday to go to it and it is two hours away. This means the cake has to be finished Friday morning so I have tonight and tomorrow late to work on it. Fortunately it is not a big cake and it is to be butter creamed with very minimal decorations. I am going to use a crusting buttercream recipe. The cakes are baked and ready to go. My question is this. Will tonight be too soon to ice the cake or should I wait til last possible minute (tomorrow) to do this. Although it is summer here in NZ it hasn't been overly humid

The sooner you can get the icing on the cake, the longer it will have for the flavors to meld together for a more moist cake.