updated 12:08 pm EDT, Tue April 1, 2014
International stores still call for 'April'
Shipping estimates for the 2013 Mac Pro have slipped from "April" to 5 to 6 weeks at Apple's US online store, checks show. At least some international storefronts are continuing to mention April, but could follow suit. Built-to-order Pros should take longer to ship as per usual.
The Pro has never been available in high quantities. The switch to a 5-6 week window may actually signal a slight improvement in supply; previous "March" and "April" targets were actually often 7 to 8 weeks ahead of delivery.