code: public function setScheduleAhead($time)
      {
          if (!is_numeric($time)) {
              throw new \InvalidArgumentException('`scheduleAhead` expects integer value!');
          }
  
          $this->options['scheduleAhead'] = (int) $time;
          return $this;
      }
docs: Set time in minutes for how long ahead CRON jobs have to be scheduled.
  .
  @param integer $time
  @return CronService