If I understand you correctly, the following macro should work. It will auto-execute when the file is opened (as long as the auto-execute option has not been deselected):
name 37697922
\0 {BREAKOFF}
{LET name;@string(@now*1000;0)}
{RANGE-NAME-DELETE "\0"}
{FILE-SAVE +NAME&".WK4";;;"replace"}
The template will be unchanged. Use for .123 format for versions 9.x (and I think you can forget the BREAKOFF line in that case too.)
In order to work backwards from the filename to the date, use:
@VALUE(NAME)/1000 in a cell with a date format.
The time can also be extracted within a fair degree of precision using a similar precision.