Auto populate data when lookup field is auto-selected

I have an email address lookup field that is auto-selected based on loginuserid:

emailToSelect = Employee[Employee_Email = zoho.loginuserid].ID;
Employee_Email_Address.select(emailToSelect);

Now, when I add a new record and on form load (not 'on success') I want my form to auto-populate additional information related to the employee that is auto-selected via the above code. The following code works, but not on 'On Add' --> "On Load'.

if (Employee[ID == input.Employee_Email_Address].count() > 0)
{
    emp = Employee [ID == input.Employee_Email_Address];
    input.Employee_Name = emp.Employee_Name;
    input.Employee_Department = emp.Employee_Department;
    input.Employee_Supervisor = emp.Employee_Supervisor;
    // etc.,
}

Appreciate any help.