Natural HR allows you to set up working patterns for your employees and allow the employees to view their working patterns in their calendar by going to 

Administration > Company > Settings > Display settings

In the 'Employee views' section, select 'Yes' from the 'Working pattern visible to employees on calendar' option

Depending on the type of working pattern that has been set up, when the employee logs in to their account, they would see something like the below on their home screen calendar, the first view is a standard working pattern with no start and end times

the second view is created from a working pattern template with start and end times. Select the week option to view the start and end times in the calendar.