It doesn't really have to be ready at a moment's notice. The time available is relatively short, but not absurdly so. The deal is order by noon, get it by 9PM, so that's (at least) nine hours to get it to you. Certainly the warehouse has to be close, but aside from that they should be able to follow the traditional model of packing orders as they go, sorting them into trucks after the cutoff time, generating routes, and having each truck deliver a full day's load in one trip.