yeah, according to wiki, its based off the Sonic Cruiser Concept, which has its roots back in the early 90's, but i tend to view the start of the 787, with the 7E7 project in 2003.

That was the plane that was similar in size to the current 787 but had extremely sweptback wing and horizontal stabilizer. Overall it looked like the current 787 on steroids. too bad they downsized the design to the current 787, but it's still an interesting plane and irrespective of the delays, selling like hotcakes