Adding the date to a static mini-loop

Hi
I have used the mini-loop from here to put the post titles on a static page.
http://codex.ww.wp.xz.cn/Creating_a_Static_Front_Page

This works well but I would like to try and include the post date as well. I read through the codex and thought perhaps adding
$np->post_date
to the line
printf ("<li><a href="index.php?p=%s">%s</a></li>", $np->ID,$np->post_title);
might work but that did not display anything (no errors but the titles were still showing)

So… Can anyone suggest a way to include the date in the mini-loop?

Thanks