When you do this with a Polyer element

  created: function() {
    console.log('created');
  },
  ready: function() {
    console.log('ready');
  },
  attached: function () {
    console.log('attached');
  },
  domReady: function() {
    console.log('domReady');
  },
  detached: function() {
    console.log('detached');
  }

You get:

created
ready
attached
domReady