src/Traits/JobTrait.php
public function setAvailableAtAttribute($value)
    {
        $this->attributes['available_at'] = empty($value) ? 0 : $this->asDateTime($value)->timestamp;

        return $this;
    }
public function setAvailableAtAttribute($value)
    {
        $this->attributes['available_at'] = empty($value) ? 0 : $this->asDateTime($value)->timestamp;

        return $this;
    }
Set available_at attribute.

@param string $value
@param $this