John -- try this code:
pre
var dateElement = Appery("date");
var date = new Date();
date.setDate(date.getDate() + 5);
dateElement.setProperty("defaultDateValue", $.datepicker.formatDate(dateElement.datepicker_dataPickerOptions.dateFormat, date ));
/pre
Note: using Date object methods setDate, setMonth, setYear you can shift initial state for the datePicker.