Add autoclose: "true"
This will help highlighting selected date

 <script type="text/javascript">
        $(document).ready(function () {
            $('#SelectDate').datepicker({
                format: "dd/mm/yyyy",
                autoclose: "true"

            });
        });
    </script>

Hi Sundance,

Until the value is selected in the date picker only "today" will be slightly marked (blue font). The circle around the number is shown after this date is picked in the input. This is the way we showcase what the input value is. Prefill option of datepicker works exactly like described in the docs. You have to add data-value="[2015,6,1]" with the given date format explained in the docs.

If you need additional help I am here for you.

Best Regards, Piotr