Corova - Angular - Ionic : Implement a loader before bootstrapping angular app

I'm using this code to bootstrap mi Angular app when I get the deviceReady event (or force it manuelly when testing in the browser):

var PhoneGapInit = function () {
  this.boot = function () {
    console.log("starting angular");
    angular.bootstrap(document, ['cmmApp']);
  };

  if (window.cordova !== undefined) {
    console.log("Found Cordova");
    var _this = this;
    document.addEventListener('deviceready', function() {
      _this.boot();
    });
  } else {
    console.log('PhoneGap not found, booting Angular manually');
    this.boot();
  }
};

//this start angular
angular.element(document).ready(function() {
  new PhoneGapInit();
});

But I would like to create a loader and hide the "dirty & unstyled" html code before the app load. Any Idea on how to do this?

Thanks