Delay Posts in RSS Feeds on WordPress

<?php
function wpcode_snippet_publish_later_on_feed( $where ) {

	global $wpdb;

	if ( is_feed() ) {
		// Timestamp in WP-format.
		$now = gmdate( 'Y-m-d H:i:s' );

		// Number of unit to wait
		$wait = '10'; // integer.

		// Choose time unit.
		$unit = 'MINUTE'; // MINUTE, HOUR, DAY, WEEK, MONTH, YEAR.

		// Add SQL-sytax to default $where. By default 10 minutes.
		$where .= " AND TIMESTAMPDIFF($unit, $wpdb->posts.post_date_gmt, '$now') > $wait ";
	}

	return $where;
}