You would need to edit the file "single.php" in you themes folder.
this file is responsible for the layout of the individual posts.
Look for a line similar to this:
Added on <a href="<?php bloginfo('url'); ?>/<?php the_time("Y"); ?>/<?php the_time("m"); ?>"><?php the_time("d.m.Y"); ?></a>
and move it to the bottom of the post.