The IHTMLPerformanceTiming::domContentLoadedEventStart property must return the time immediately before the user agent fires the DOMContentLoaded event of the document.
HRESULT value = object.get_domContentLoadedEventStart(ULONGLONG* p);
An ULONGLONG value that represents the time immediately before the user agent fires the DOMContentLoaded event of the document.
- Navigation Timing, Section 4.2
The value reported by the IHTMLPerformanceTiming::domContentLoadedEventStart property represents the number of milliseconds between the recorded time and midnight January 1, 1970 (UTC).
Windows Internet Explorer 9. This property is supported only for documents displayed in IE9 Standards mode. For more information, see Defining Document Compatibility.