UPDATE: NASA officials just completed a teleconference in which they said November 2018 is a No Later Than date. They are hoping to do much better; there’s still a chance of launching in December 2017 or sometime soon afterward.
NASA just announced an 11-month delay in the first Space Launch System flight from December 2017 to November 2018 in the fourth paragraph of a press release.
This decision comes after a thorough review known as Key Decision Point C (KDP-C), which provides a development cost baseline for the 70-metric ton version of the SLS of $7.021 billion from February 2014 through the first launch and a launch readiness schedule based on an initial SLS flight no later than November 2018.
The full press release is below.