How to count working days from a start date

Use function "caladddays".

And this "caladddays" function will calculate based on your calendar where you set working days and non-working days for a period

1. Either the Default Process Calendar or a new Process Calendar can be chosen. If a new Process Calendar is created, this should be explicitly mentioned as the second argument to the caladddays() else the function consumes the Default Calendar.
2. Definition of Non-working days to be set up in the Process Calendar(again, either in the Default Process Calendar or new Process Calendar created specific to the module)
3. While exporting to other environments, the same configurations should be made explicitly(creation as well as the setting of non-working days) as there isn't a way to package and export the Process Calendar or its settings.

@issamd Suggestions made above by other practitioners should work fine as long as the above-mentioned are taken care of.

Thank you all for your suggestions, this worked very well!