functions.php

<?php
add_filter( 'user_has_cap', function($all, $caps, $args, $user){
    if (!in_array('contributor', $user->roles))
        return $all;

    $posts = get_posts(array(
        'post_type' => 'post',
        'post_status' => 'publish',
        'posts_per_page' => 1,
        'author' => $user->ID,
    ));

    if (count($posts)>1)
        unset($all['edit_posts']);

    return $all;
} );