Pierre,
If you are shooting Canon or Nikon, and you give the camera a user name or comment (respectively), you can use the {id} variable (this is essentially {user} on Canon and {comment} on Nikon). If this is set to the user's initials then you are done. But if it it is set to, say, "John Doe", then just rename the ingested folder from "John Doe{month0}{day0} xxx" to "JD{month0}{day0} xxx" after the ingest is complete.
--dennis