https://time.com/alien-life/
The Milky Way has around 100 billion (1011) star systems that could conceivably host intelligent life under our current assumptions. An estimate of 100,000 (105) active civilizations in the galaxy would mean one per million star systems. At the exponential rate of growth in signal processing, researchers will have examined one million candidates by around 2034, bringing the odds of a discovery into the probable. Adding or removing a zero from the estimate of the number of civilizations out there merely adds or subtracts six years from the estimate, respectively, since that's how long it takes to expand our search proportionally. See you in 2040, aliens.