Looks like you asked this question elsewhere,
For reference:
<?php
echo '<ul id="timeline">';
echo '<li>Latest</li>';
$prev_month="";
$prev_year="";
$args = array(
'posts_per_page' => 10,
'ignore_sticky_posts' => 1
);
$postsbymonth = new WP_Query($args);
while($postsbymonth->have_posts()) {
$postsbymonth->the_post();
?>
<li><a href="https://wordpress.stackexchange.com/questions/50592/<?php the_permalink(); ?>"><?php the_time('j'); ?></a></li>
<?php
if(get_the_time('F') != $prev_month || get_the_time('Y') != $prev_year && get_the_time('Y') == $prev_limit_year) {
echo "<li>< ".get_the_time('M')."</li>\n";
}
$prev_month = get_the_time('F');
$prev_year = get_the_time('Y');
}
echo '</ul>';
?>
I do not claim this works but I will assume the original author tested this before providing his answer, if his personal website is anything to go by.