"Glotto-chronology" is "glosso-chronology".
Here I found an article using the term.
Indeed, we can speak with certainty of Indo-European history and geography only in the vaguest, most general terms, which has not stopped scholars, however, from trying various means to determine the time and location of the original Indo-Europeans. For instance, based on calculations of the general rate at which languages change, attempts have been made to reason out how long ago Proto-Indo-European began to break apart. That is, by looking at how different its daughter languages are, it may be possible to get a sense of how long it took to create that number of variations in grammar and vocabulary evidenced in Indo-European languages.
This is called glossochronology and, though some linguists endorse this method of measuring language change, it has not found widespread favor among scholars. The fact is that the rate of language change can vary widely according to circumstances—languages sometimes evolve quickly and other times slowly—and none of it is predictable. All in all, the original Indo-European culture almost certainly existed at some time between 5000-2000 BCE, but such a wide range is not very helpful to those trying to assess the Indo-Europeans' role in history or tie them to particular developments in a certain age.
paco