hello @VI3DS 

I hope you are doing great. You are updating the attribute with due date right? if so then i can explain you the solution for updating due date according the set months in “review and send for signature step”

here is what you can do:

1. Add “Update Variable Value” step after “review and send for signature” step. and update the current date with the any date varible.
 

2. Create one more final due date variable just like i did “Due_Date2” and here you will need to write the c# code
   Code = DateTime.Parse(GetVariableValue("due_date")).AddMonths(2);
    and if you adding 6 months then write 6 instead of 2 in the example.
   and the apply “update document metadata” step and update your due date.
   
   Thanks!