I would like to create a calculated value for the mandatory Title field:

<username, created by> - DD-MM-YYYY

That is I want the title to be filled ind with the user name (the user that creates the item) and the date (for creation). Can this be done automatically and if so, what should I put in the field below the "calculated field" radio button. If this cannot be done this way, I can use a workflow to set the value, but what should be the choice of workflow? 

(sorry if the naming is a little off target I'm not working with an english version of SharePoint).