Setting due date one month prior to expiry date

I want to set the due date for all my domain names to one month prior to the expiry date.

For instance, a domain that expires on May 1st should be due on April 1st.

I'm making a script to automatically set the new due date, but I'm wondering if this would cause any unforseen problems, such as WHMCS cancelling the domain with Enom when the due date is passed?