From the article: "It sounds feasible and probably worth pursuing," says M. Flint Beal, MD, the Anne Parrish Titzell professor of neurology and neuroscience at the Weill Medical College of Cornell University. He also reviewed the findings. He is also developing an early blood test for Parkinson's disease that uses a different approach.
It sounds like the test has not been developed yet. I'm not sure how long it takes for a test to become standard but I would guess it is quite a while off!