How do I automatically add a date and time to the filename of a batch of scanned documents

Problem is - When I scan batches of invoices into searchable pdf files, I have a default file name

eg. needs_processing,

that automatically enters into the filename, and before I click save in order to prevent it just replacing the existing file name, I am manually typing the date and time at the end of it.

eg. needs_processing 30082017 16.34.pdf

I am scanning batches of documents into searchable pdf files.  I don't want to type the file name every time, and so thought if the date & time was automatically added to the end of the pdf file name, (think this is called Suffix) then it would not replace the pdf file but just create new ones.

In an ideal world I would like softwear to find the invoice number in the document (invoices) and name the pdf that invoice number. But think that may not be possible, however , any work arounds you may have would be greatly appreciated?