A delivery day sets transport cost and also how many fresh days the product has on the shelf. The plan is built from four inputs, and the order matters:
- Receiving window: the days and hours the store accepts goods. A vehicle arriving outside it waits or turns back.
- Remaining shelf life: the label date minus the days spent in transport and in the store's back room.
- Selling days: how many days the product takes to sell out, and which days of the week carry the sales.
- Production calendar: the day the product is ready to dispatch.
Take a product with five days left on its date, going to a store whose sales cluster between Friday and Sunday. Delivered on Monday, it reaches the weekend on its last day. Delivered on Thursday, the same product meets the three busiest days fresh.
A change of day is first trialled with one group of stores, and sales, waste and days with an empty shelf are compared with the previous period. Changing the day across the whole network at once hides what caused the result.
