Do you mean delivery from the dealer to the customer ? or from the plant to the dealer?
Dealer to customer there could be a 1-3 day delay depending on their process. Check in of truck, check truck for damage and operability, remove protective film, contact customer, set up financing etc.
Plant to the dealer is mostly shipping logistics - The plant doesn't really want any vehicles hanging around their log, so it's in their best interest to get it out. Usually shipped by rail car. So trains have to be available. Then from nearest rail yard to final destination on trucks. Weather conditions play a major part in the logistic chain. The Trucks come from Michigan or Mexico. If coming from Mexico, there could be a few delays at customs as well.