Why the slider plugin show before it is ready to generate?

I use the jquery slider plugin "slippry" :

http://slippry.com/

I followed the tutorial and write like this:

 $(document).ready(function () {
                $('#item').slippry();
            });
        </script>

And Html

        <ul id="item">
            <?php
            foreach ($banner_list as $key => $banner) {
                echo "<li>";
                echo "<a href='#slide'" . $key . "><img src='" . site_url("banner/" . $banner["image_url"]) . "'></a>";
                echo "</li>";
            }
            ?>
        </ul>

The problem is , there is a second that the slider show when it is not ready.

And in a second , it is generated and show like this

Also , if I press f5 then it will not have this problem (perharps cached?) but when I press the enter at address bar to enter the page again it has the same problem again. How to fix the problem ? Thanks