Check GearInStock, https://www.gearinstock.com/nvidia-rtx-5090-pre-order-in-stock-availability-tracker/ They will alert you when in stock.

So, I’m not sure about the exact day, but I’ve heard from some industry contacts that the next big shipment might be delayed slightly to accommodate minor revisions to the power connector housing. If you're hunting for one, keep these reliability factors in mind:
* Stick to authorized vendors only to protect your RMA rights on such high-TDP hardware.
* Verify your PSU meets the latest ATX 3.1 standards—these cards have massive transient spikes.
* Avoid the temptation of 'open box' units right now unless you can verify the thermal pads haven't been messed with. I think availability will stabilize once the initial hype dies down. Honestly, don't compromise on safety just to get a card a week early. Dealing with a melted 12V-2x6 header is way worse than waiting for a restock from a reputable source.

Maybe next month.