It is recommended to schedule a service appointment for your Sub-Zero appliance as soon as you notice any issues or require routine maintenance. Service providers for Sub-Zero appliances can have busy schedules, especially during peak seasons, so it's best to call and schedule the appointment as early as possible. This will help ensure you get a convenient time slot and avoid prolonged downtime for your appliance. If you wait too long, the problem may worsen, and it could take longer to get the appointment you need. Promptly scheduling a service appointment can help address any problems and keep your Sub-Zero appliance running smoothly.