As of October 2nd, 2014, the Service Times feature will also include the ability to create Service Exceptions. If you already use the Service Times feature (Appointments Preference #6), you will see an extra "Service Exceptions" option for each of your existing services.
Service Exceptions can be used to restrict service availability for specific days. Service Exceptions override Service Times, making it possible to change the times your services are offered on a daily basis. This feature is available for all price tiers and versions of the system.