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

Why do I need to choose a slot before I place my online groceries sainsbury delivery slot For those without a Delivery Saver plan, Tesco Delivery and Click+Collect slots will open for all customers on November 21 at 6am It says the sainsburys book a slot But North Wales Live discovered there wasn't a single delivery slot available for the main supermarkets, as every one appears to have been

sainsburys book a slot Has your Sainsbury's delivery not arrived? Someone asked: “Can you confirm if our delivery will be rebooked for ASAP, or will our slot be

sainsbury book a slot Sainsbury's said on their website: We've been working hard to expand our service across home delivery and we are now able to offer home Sainsbury's shoppers who order before midday will now be able to choose a delivery slot on the same day after 5pm, or a collection time at