Following the Admin Guide, First, we should create a working calendar  (Administration >SLA Calendars > Calendar Management), by clicking in the button 'Add a calendar'

Create a name

Only the name of the working calendar is a mandatory field

Set the working days/times

• For this calendar, the working days are from Monday to Friday,
• The working times are from 09 am to 05 pm
• Except for Friday,  the working times are from 10 am to 05 pm

Add the holidays to the calendar

The repeated checkbox allows us to configure the annual holiday ( ex: New year, Christmas...)

You can see the configuration of the new calendar (Simple Working Day)

You can modify or delete the calendar (1)