This is the latest I could find on the general internet referencing the study I saw in brief in one of my Archeology magazines:
Using data from over 160 languages, a new study explains where, when and how Indo-European languages spread across Europe and Asia.
theconversation.com
To summarize, this data is from a more recent study done in Germany that referenced a much wider range of linguistic samples. From this article, it appears that the tentative conclusion was that Proto-Indo-European originated about 6000 BCE in the south Caucasus/eastern Anatolia region and from there spread in all directions: west into eastern Anatolia and ultimately Greece and the Balkans, north to the Pontic Steppe from which a secondary spread took it into central Europe several thousand years later, and east into (modern) Iran and India.