No matter if you ignore him, help him, or hinder him, it will still take some time to get all the way to Falkreath with a load like the Night Mother on the cart.
If you remember correctly, Cicero is currently on the road north of Whiterun waiting for his wagon wheel to be fixed. When you begin the 'Destroy the Dark Brotherhood!' quest, you would have to meet Astrid in the abandoned shack prior. Well, let's look at the technical side of this.
