409 status code - Duplicate-Invoice error

Referring to the announcement available here. Is there any information on when this change will be introduced in the simulation environment? As I understand, the production release date is not yet confirmed.

Currently, we were unable to receive the 208 status code for clearance invoices, on simulation environment which prevents us from testing the changes in our solution. Additionally, the sandbox documentation (Zatca) lacks an example of such a response.