Date Field in Adobe Acrobat X

I have a form that users fill in. One of the fields on this form is a date. Through the properties I have set the date format of dd/mm/yyyy. What I was hoping to be able to do next is, get it to auto populate. So when the field onFocus it executes something similar to the now() you can use in MS Access etc.

Is there a way of getting it to add the system date automatically if so, how?

Many thanks in anticipation of a speedy helpful response

Kindest Regards

Toni