How often does the supermassive black hole in the Milky Way become a quasar? My current interest is black holes and quasars. I was wondering how often they erupt--specifically ours? Would it be blindingly bright on Earth? Finally, would there be any effects that would alter our life on Earth that we know of?
To answer your question, the black hole in the milky way was never a quasar, and as it currently stands will never become one.

Info about how earth and life on earth could be affected if this ever happened, can be found here.