Add post dates from child theme and change font size on homepage post

Adding the date is potentially as simple as inserting the_time() in the appropriate place in the template if you’re editing the template files.

However, it looks like you’re using a child theme, so we have to use WordPress’s system of filters.

To add the date to the post, try filtering the titles. Add this to your functions.php:

function add_dates_to_title_wpse106605($title, $id) {
    if (is_home() && in_the_loop()) {
        $time = get_the_time( $d = 'l, F j, Y', $post = $id );
        return $title . '<br><small class="time">' . $time . '</small>';
    } else {
        return $title;
    }
}

add_filter('the_title', 'add_dates_to_title_wpse106605', 10, 2);

You can see that I’ve configured the $time to be output with the 'l, F j, Y' bit. Check out the Formatting Dates And Times page for more info on that syntax. It’s pretty straightforward.

You’ll also notice that I prepended it with a <br> tag to move it onto the next line and wrapped it in in a <small> tag. I’d recommend getting rid of the <br> and just forcing it into the next line by targeting it in the CSS and adding display: block;. Obviously, change the HTML to suit your needs.

For the CSS change, you need to have at least the same amount of specificity as what you’re trying to override. The easiest way to do that is just to copy it. This should do the job:

@media screen and (min-width: 600px) {
    .entry-header .entry-title {
        font-size: 18px;
    }
}

Obviously change the size to suit your tastes.