How to pre-set the date in the text box control before popup calendar is displayed

How to pre-set the date in the text box control before popup calendar is displayed

Hello. I am using the JQuery popup calendar control. I pre-set the date to today's date, and that date is pre-selected in the calendar when it pops up. however I would like for the default date to be automatically be copied to the text box before the calendar is even displayed. Does anyone know how to do this?