The easiest method is to create a template at Advanced - Display/Modify Templates with name "FileNameWithDateTime" with following content
Press key F1 when the dialog is open to see help about templates and what this string means.
Remember the number of this template, for example 0 for your first template.
But before you create the template, specify at Advanced - Configuration - Directories the Template Directory for the template file Uetmplte.dat.
After you have created the template, you can insert this special date/time string with "Order" before and ".csv" after with a hot key assigned to the InsertTemplateX command, or with Advanced - Insert Template, or with Advanced - Individual Templates, or via the Template List (View - Views/Lists - Template List), or with a macro.
Here is the macro which inserts temporarily at top of your already modified file the template, cuts it to user clipboard 9 to next save
the file with this string in the file name. ^c is the place holder for the clipboard content as described in help about macro command SaveAs.
The big advantage of using a template instead of macro command TimeDate is that with a template you can define how the date/time string should look like. The TimeDate command inserts full date and time in the format specified in the Regional and Language Settings of Windows of the current user. And it's not a good idea to modify this Windows setting.