Get first comment link on the post itself

you can get comment link by wp function

$args = array(
    'number' => '1',
    'post_id' => your_post_id, // use post_id, not post_ID
);
$comments = get_comments($args);

    <a href="https://wordpress.stackexchange.com/questions/108654/<?php echo get_comment_link( $comments->comment_ID ); ?>">postname</a>