I believe that this strongly depends on your visa office and its capacity to process renewals. Central intake issues a request for renewal (after re-examining your case, expired meds, pcc...) and dispatches the request to the relevant visa office which sends out your ppr down the line knowing that the office has capacity to issue you a new counterfoil and COPR doc. Eitherway, they mentioned that they are almost done with pre Mar 18 COPRs and there are 23,000 post Mar 18 COPR with expired, expiring or valid dates. I also hope that the wait is not too much.