if the bird flu started spreading between humans, how long would you need to stay quarantined before it was safe to come out??

Im talking worst case scenario, something like Station 11 or the movie Contagion

If the bird flu started spreading rapidly from human to human, and it devastated our population as it can in birds or marine life, how long would one have to hole up in seclusion before the virus burned through the population and it would probably be safe to come out.

Obviously, this is not the current situation, and this scenario is a long way from becoming any type of reality. This is just a hypothetical. If turds hit the fan, I dont want to waste time trying to figure this out in the moment while everyone's ill, and can't answer.

Move over B's, I want first dibs on the tp!

Edit: I'm not thinking of a flu, as it behaves in the human population as we know it. I'm talking like zombie virus, without the worry of reanimation. Like, pretty much, everyone that catches it, dies, and it spreads fast and stealthily enough that the end result is a drastically lower population of survivors. How long would a person have to stay isolated to outlive the worst of it.