JavaScript to save as current date

I have a time form called Timesheet Paperless.pdf I send this form to an employee and tell them to fill in their name and employee number on the form. Then I'll ask them to go to File> Save As and name the form INTIALS_TS.pdf. Now I would like to have a button with a form in the form that will open the "Save As" dialog with the file name INITIALS_TS CurrentDate.pdf under "My Documents / Work Files / Temporary Sheets /". Therefore, each new payment period, they click on the save button in the form to save the file in a folder with temporary sheets with their names and the current date of pressing the button. How do I do this in JavaScript?