Dell does not "stock" anything.  They're built to order and shipped from the manufacturer. Given the shortages of both components (CPUs and GPUs) and shipping space (bear in mind the systems are built in China and shipped directly from the manufacturer, delays are the norm and not the exception these days.  
I recently ordered an R10 Aurora and I chose the specific model because of its 'fast track delivery'. All seemed well and it was MEANT to ship on the 3rd of June with an expected delivery for the 11th of June. However, I have now just received a revised shipment that has a new arrival date of July 5th. This is ridiculous, a big part of my decision to purchase the machine was the delivery turn around time. How can it jump a whole month?! I spoke to a sales member and he said they had the computers in stock and now suddenly I need to wait a month.This has been a horrible experience, chasing it up for days only to hear it gets delayed by a whole month.
Order delayed