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Instacart releases slots throughout the night. 2am to 5am are great for getting one. There are many currently lesser known delivery systems - search for ones targeting minorities. For example Yamimeal (despite having meal in the name - they do groceries). Also, buy bigger orders if you can. I have been getting at least a couple hundred dollars at once, good for 7-10 days. I would get more at once, but I want to eat s…
> throughout the night We haven't tried at very odd hours as you suggest; we'll give it a try, thank you.
* Whole Foods (for delivery) releases slots at midnight. This is pretty obvious, because you'll actually get what is basically a, "rate limiting" dialog page if you don't start checkout successfully. The site is getting slammed THAT hard. So for 2-3 minutes, hope you actually can get to the page to confirm placing the order. Those slots go FAST (* Amazon Fresh seems to start releasing slots at 12:30AM. These seem fairly easy to get at release. No rate-limiting page for checkout.
* Instacart seems to have a "semi-hold" for orders in carts that aren't yet confirmed orders. I can watch delivery slots for the next 2 weeks disappear until none remain. But at midnight, they become wide open as soon as 3-4 days out. If you're on point, you can get one early in the day, where stock is likely good, or late in the day, where places like ALDI will have replenished the shelves since the rush is before noon.
Amazon (Whole Foods and Fresh) seem to only hold items in a cart so long if you've not purchased. I've not nailed it down yet, but it's measured in "hours" (not sure of the number), not days. My recommendation is to have a firm list and start filling your cart 60-90 minutes before the above times. That seems to get everything committed in the order 100% of the time.
If you're trying to stock up to not have to go out for a good while, consider a, "defense in depth" strategy. Place a Whole Foods order, place a Fresh order, place an Instacart order. Stagger them by a few days. If something comes in the first two orders, remove it from the Instacart order. You may be able to cancel the Instacart order several days in advance, and still have gotten basically everything.
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I'm done buying groceries online for a long while, so rather someone who could use it have the knowledge I learned through far too much effort trying to figure out how the black boxes worked. Legitimately felt like I was routing a speedrun for a grocery video game to get a world record.