nn = (Today() - Informat( "01/01/1970", "m/d/y" ) - In Hours( 8 )) * 1000;
This will give you the number of milliseconds from the current date/time, to the current second. I am not aware of how to get Today() to the millisecond. There are the functions of HPTime() and Tick Seconds() that can measure at sub second times, however, their base start point, is JMP session start time and I don't see how one would be able to work them together.
Jim