import-tweets.php

<?php
/**
 * Quick and dirty way to import a Twitter export into WordPress
 */

define('WP_USE_THEMES', false);
require './wordpress/wp-load.php';

$username = '<your-username>';

$tweets = file_get_contents('tweet.js');
$tweets = json_decode($tweets, true);

foreach ($tweets as $tweet) {
    $datetime = DateTime::createFromFormat('D M d H:i:s P Y', $tweet['tweet']['created_at']);
    $datetime = $datetime->format('Y-m-d H:i:s');
    $post_id  = wp_insert_post([
        'post_status'   => 'draft',
        'post_type'     => 'iwcpt_note',
        'post_date_gmt' => $datetime,
        'post_date'     => get_date_from_gmt($datetime),
        'post_title'    => '',
        'post_content'  => $tweet['tweet']['full_text'],
        'meta_input'    => [
            '_share_on_twitter_id'  => $tweet['tweet']['id_str'],
            '_share_on_twitter_url' => 'https://twitter.com/'.$username.'/status/'.$tweet['tweet']['id_str'],
        ],
    ]);
}

Should probably have added a check for in_reply_to_status_id_str and import these last and link them, if applicable, to previously imported Tweets, using a meta search and the u-in-reply-to microformat.