We've now instituted a policy of doing a 'stock check' once a week on a fixed day, 1.5 days before the online groceries order deadline, and it's really helped a lot to make sure that we don't unexpectedly run out of stuff!

Literally just a list of "thing, minimum we should have, maximum we should buy up to, where to buy it", and then printing the whole list and going through it marking how much we have of each. What we can (plausibly/affordably) order online, we do; the rest we get from the store in person.