The Astrobiological Copernican Limit
https://iopscience.iop.org/article/10.3847/1538-4357/ab8225
36 civilizations, roughly 17000 ly apart.
http://www.sci-news.com/astronomy/communicating-extraterrestrial-civilizations-milky-way-08536.html
No, I don't pay too much attention to this type of speculative analysis, but it does give you an idea of what the latest thinking in the field is.