Helli Evi.

The availability of services is determined by the Work Hours and Special Days of your employees. If the employees have working hours from Mon - Fri, from 09:00 - 17:00, all services the employees are assigned to will be able to provide appointments during those times, dependent on the duration of each service.

Special Days overwrite regular working hours, so if your employee is working from 09:00 - 17:00, you can create a special date for a certain date or date range, and override those hours. Please note that Special Days cannot overwrite Days Off.

So, in your case, you'd need to create a Special Day for this date in your employee's profile, assign it to a specific service, and it will override the default working hours of that employee.

Events and Services are two different features, and they can't be used together, but please note that if you assign an employee to an event, under "Staff", this employee will be unavailable for appointment bookings as long as the event lasts.