Today (Friday) The earliest slot at Ocado (A big established grocery delivery service / Online supermarket with own robot warehouses etc, in the UK) will give me is Sunday morning. I do not know if this is due to cut-off times or slot availability but it is moot.
I'm not worried, I plan these orders weeks in advance (and you can add or remove until the night before).
Other smaller services (e.g. Deliveroo, weezy, gorillas) will come much faster, but they typically just collect and cover the last mile. This seems to be a growth area lately, two of those companies are new.