if you absolutely want to use that SO code

fdsafsad.js

// snippet for SO: http://stackoverflow.com/a/14138133/670023

// Never do this. Handlers inside of handlers is a Bad Idea regardless of whether they're once or not.

google.maps.event.addListenerOnce(map, 'tilesloaded', function(){
    //this part runs when the mapobject is created and rendered
    google.maps.event.addListenerOnce(map, 'tilesloaded', function(){
        //this part runs when the mapobject shown for the first time
    });
});

// i'm not saying that answer is correct, but if you absolutely want to use that solution, do this instead:

var tilesLoadedCount = 0;
google.maps.event.addListener(map, 'tilesloaded', function() {
  tilesLoadedCount++;
  if (tilesLoadedCount === 2) {
    
  }
});

thanks for your gits, maybe last tilesload subscription is the question to be solved, I try to debug for "last change of tiles loaded before idle map", and my research found nearly your solution:

google.maps.event.addListener(map, 'tilesloaded', _.after(function() {
  // you are sour to refresh or center bounds
}, 3));