DATE is the COM Automation type. You can use VariantTimeToSystemTime or VariantTimeToDosDateTime :

DATE JobStartTime;
CurrentJob->get_StartTime(&JobStartTime);
SYSTEMTIME st;
VariantTimeToSystemTime(JobStartTime, &st);

You can then also turn it into a FILETIME using SystemTimeToFileTime:

FILETIME ft;
SystemTimeToFileTime(st, &ft);