public function setNextToBePublished()
    {
        $next = $this->find()
            ->where([
                sprintf('%s.active', $this->getAlias()) => true,
                sprintf('%s.created >', $this->getAlias()) => new Time,
            ])
            ->order([sprintf('%s.created', $this->getAlias()) => 'ASC'])
            ->extract('created')
            ->first();

        $next = empty($next) ? false : $next->toUnixString();

        Cache::write('next_to_be_published', $next, $this->getCacheName());

        return $next;
    }