Integrating Deluge in zoho people to setup a custom function in workflow automation

So basically i have a probation form in which their is a field "Date of Confirmation", "Probation Assesment", "Date of Joining", "Employee ID". so when Date of joining will not be empty then i want this to be triggered. so if "Probation Assesment" is Satisfied then i want the date of confirmation to be updated by Date of joining + 3 Months and if the "Probation Assesment" is Not Satisfied then date of confirmation should be Updated by Date of joining + 6 months.