Within six hours of opening the pre-order online window to nab an Apple (AAPL) Watch, the vendor had sold out all models of the device with backorders set at a minimum of 4 – 6 weeks to ship, according to a number of media reports.

At this point, it’s not clear if the backorders owe to high demand or inadequate supply. In the U.S., the 38mm Stainless Steel Case with Black Classic Buckle was the only remaining Watch model offering an April 24 – May 8 shipment window but it, too, ultimately slipped to 4 – 6 weeks, according to reports.

9to5Mac reported that while availability depends somewhat on the individual SKU, in the U.S. the Apple Watch and Apple Watch Edition models aren’t expected to ship at least until June and the Rose Gold Apple Watch Edition won’t end up in shoppers’ hands until July. Product availability is worse in other geographies with some Watch models delayed in shipment for six months, the report said.

On Thursday, ahead of the online order launch, Apple retail boss Angela Ahrendts warned of constrained supply at launch with a statement that the vendor expected demand to breach supply.

“We are excited to welcome customers tomorrow and introduce them to Apple Watch, our most personal device yet,” Ahrendts said. “Based on the tremendous interest from people visiting our stores, as well as the number of customers who have gone to the Apple Online Store to mark their favorite Apple Watch ahead of availability, we expect that strong customer demand will exceed our supply at launch,” she said.

In confirming earlier reports that Apple planned to confine its pre-orders for the Watch to online requests, Ahrendts said, “To provide the best experience and selection to as many customers as we can, we will be taking orders for Apple Watch exclusively online during the initial launch period.”

Apple’s Watch wasn’t its only backordered product. The vendor’s new 12-inch Macbook with Retina display is out of stock at many of the vendor’s Apple Stores in North America and the U.K., limiting orders to online along with a 3 – 4 week wait at best, according to a MacRumors report.