I want to be able to insert a fixed (not updated) date in the heading of a letter so that if I go to print it the date is not updated

I want to be able to insert a fixed (not updated) date in the heading of a letter so that if I go to print it the date is not updated.

‘Insert’ > ‘Fields’ > ‘More Fields…’ > ‘Document’ > ‘Date(fixed)’ > choose format > ‘Insert’

You may abbreviate the procedure using Ctrl+F2 as hotkey.