There is allways a chance for the EB-2 worldwide category to go into retrogression.
If your PERM was for the same job, your RIR is invalidated anyway.
Once your PERM is approved, I would file immediately, it sort of secures your position. While your PD is later, by having a pending I485, you will allways be able to get EADs and APs and a legal status. The later PD has a lower potential to bite you than a decision to defer filing of the I485.
Also, if your RIR is for a different job, you can file a second I140 for this job (which will have the earlier PD). If there is any retrogression monkey business later on, you could either file a second I485 or transfer the case to the I140 with the earlier PD once it is approved.