According to our well-informed sources the engineering samples were expected in Q4 2016 which starts in October. Remember, we were the first to mention Naples in detail in June 2016. Sometimes AMD calls these products  Alpha versions  but it looks like AMD was able to demonstrate the CPU a bit earlier as it did a public demonstration at the event in San Francisco last week. This could have  been a pre-Alpha version that was stable enough to run.   
The beta version will follow Q1 2017 and this CPU should be the pre-final version before the company goes to initial production. There is another step in between called the final/general sample that is expected in Q2 2017 and  followed by initial production.