The Surface Pro 3 is slated for release later this Friday, but only for the Core i5 versions coming in 128 GB and 256 GB ranges. The more budget friendly Core i3 and wallet-busting Core i7 configurations, however, are not due until the end of August.
Microsoft may be dealing with somewhat high demand though, as the $999 Core i5 version with 128 GB now has a June 30 ship-by date, slipping by 10 days from June 20. The change in shipping appears only to apply to new purchases, and not early pre-orders. Accordingly, if you reserved your Surface Pro 3 128 GB prior to the last 24 hours, your new tablet/laptop hybrid should still be on track for delivery.
Presumably, Microsoft and Best Buy will also have the128 GB version on-hand in stores for immediate purchase starting Friday as well.