you would add it to the list or arguments or configuring the datepicker.
the datepicker is created using this section of code:
$(function(){
$('#datepicker_27').datepicker({
dateFormat: 'yy/mm/dd',
showAnim: 'show',
onClose: closeDatePicker_datepicker_27
});
});
add the default date to the list of arguments:
$(function(){
$('#datepicker_27').datepicker({
defaultDate: '+30d'
dateFormat: 'yy/mm/dd',
showAnim: 'show',
onClose: closeDatePicker_datepicker_27
});
});