On February 1, 2017 Boeing rolled out the first 787-10 Dreamliner from it's final assembly facility in North Charleston, SC. ZC001 (LN 528, N528ZC) was taken to Bay 1 of the newly opened paint hangar where it will get it's coat of paint and perhaps get some ground testing done as well. It will be powered by Roll Royce's Trent 1000-TEN engines currently undergoing certification testing on the fourth 787-8, ZA004 (LN 004, N7874). This aircraft just recently returned from Victorville, Ca and is now flying around Colorado Springs. Given the increased tempo of test flights with the new Trent engines, it seems that Boeing is gearing up for the B1 flight very soon.
The 1st 787-9 conducted its B1 flight 24 days after being rolled out of Everett's 40-26 building. Right now preliminary information indicates a flight for ZC001 around March but I suspect that it could take place late this month though this date is all dependent on the ground gauntlet testing that is required prior to the first flight.
Still the -10 is a simple stretch of the 787-9 and has 95% commonality with its smaller sibling thus this initial testing should go smoothly given Boeing's experience with building and flying the 787-9. My prediction for a range of first flight dates is between February 21 and March 7.
In the meanwhile Boeing should begin assembly on ZC036 (LN 548) around the third week of February. This will be the 2nd 787-10 to fly and the first equipped with GEnx-1B engines. To me it seems that Boeing is executing extremely well on the 787-10 thus far but the year long test flight program is still lie ahead which can uncover unknown unknowns.