<script type="text/javascript">
    //ExecuteOrDelayUntilScriptLoaded(CreateCallOutPopup, "callout.js");
    _spBodyOnLoadFunctionNames.push("CreateCallOutPopup"); // use the '_spBodyOnLoadFunctionNames' instead

    function CreateCallOutPopup()
    {
        var targetElement = document.getElementById('LaunchCallout');
        var calloutOptions = new CalloutOptions();
        calloutOptions.ID = 'notificationcallout';
        calloutOptions.launchPoint = targetElement;
        calloutOptions.beakOrientation = 'leftRight';
        calloutOptions.content = 'content';
        calloutOptions.title = 'title';
        var displayedPopup = CalloutManager.createNew(calloutOptions);
    }
</script>
<div id="LaunchCallout" style="width: 150px;">LaunchCallout</div>