On 20 Sep 14 I was able to get on the USS Nimitz during Fleet Week in San Diego. One of the sailors I spoke to said he was looking forward to the next task which was trials with an aircraft that had never been on a carrier before. Unless there is some new "black" aircraft, I assume that this will be the F-35C as per this earlier report:
Navy's F-35C Completes Landing Tests Ahead of October Sea Trials - USNI News
If correct, this would mean no slippage to the plan since Jan 2014.