It looks like the Canon EOS 5DS and 5DS R will begin shipping in just over a week on June 14, 2015. B&H has listed the new shipping date subject to availability.
As with other high-demand cameras, it may take a few weeks to fill all of the pre-orders. So if you want a 5DS or 5DS R sooner rather than later, you’d better go ahead and get in the pre-order line now. Check it out here at B&H Photo.