If you want Saturday delivery of your NZ Post CourierPost parcel then you must purchase one of these tickets.
This is an option provided by NZ Post CourierPost for their parcels (only their parcels) to be delivered on a Saturday, if they have been picked up on a Friday, rather than on the following Monday.
You will need to use their Tools menu item to see if your address allows the purchase and use of a Saturday Delivery ticket.
Check it out at https://www.courierpost.co.nz/tools/address-checker/
Its a service for those who can't wait.