Why do I need to choose a slot before I place my online groceries

Sainsbury's Christmas delivery: How to book and what to order sainsbury book a slot When booking a delivery slot with Sainsbury's, you have until 11pm the night before to amend your order They are now offering 700,000 weekly sainsburys delivery slot Sainsbury's customers who have a Delivery Pass could book their Christmas food order from November 23 Other shoppers were able to secure a slot

sainsburys book slot Cancel Sainsbury's delivery slot? I signed up to see how much an item would cost to deliver and it's come up £7 with a delivery slot booked