We have both RUM & synthetic testing up and running we should start to focus on what to measure and find metrics that means something for the user and are easy to communicate.
When the article text is showed for the user. Maybe when the article headline is shown? "Time to text"?
Upstream Google has been working on a "First Meaningful Paint" in Lighthouse:
They're also working on exposing this through a new Paint Timing API.
EDIT: This has been released in Chrome 60.