How to tell if tinyMCE has been initated?

I know this question is old, but...in case someone is still looking for the holy grail:

in tinymce 4, you can pass a callback to tinyMCE.init like so:

tinyMCE.init({
  //your regular parameters here...
  setup: function(editor) {
    editor.on('init', function() {
      //all your after init logics here.
    });
  }
});

You can use tinymce.editors.length to see if there is already an editor instance initalized (tinymce.editors.length > 0).