public function monthly()
    {
        $this->setScheduleMonth(self::ANY);
        $this->setScheduleWeek(self::NONE);
        $this->setScheduleDayOfMonth(1);
        $this->setScheduleDayOfWeek(self::ANY);
        $this->setScheduleHour(0);
        $this->setScheduleMinute(0);

        return $this;
    }