I have a little knowledge of the changes to the Reserve Engineer units; the MND signed off the MOOs last December. That was the day the change occurred legally. The CFOOs have almost caught up (except for a glitch in one that has it being re-drafted even as we speak).
The lack of an overall co-ordinating directive for the process, which would have brought together all the details for the change, is a major failing in the whole process. In reality, the name change is the easiest part of it... it's working out the DAs, signing authorities, powers of punishment... that make the whole thing difficult.