Well, and now we can listen and broadcast. So only 40-80 years before we hear something!
And, by then, we'll be able to see them better anyway.
These are all probably sad, windswept rocks. Our descendants will barely eek out a living on them in 250 years, go quietly insane, and then murder each other while the Earth devolves into the Great East-Wast War and forgets about them.
All so sad.