Yes start it there by gathering all the necessary documents while your PR application is on the process. By the time you get your PR, you are already halfway to your RN license especially now its pandemic. You have 2 options to get your license, bridging program or taking all the necessary exams. Some applied for ontario license as they say its easier/faster then transfered their license here. Some took the License Practical Nurse exam while waiting for their RN as it takes longer for RN. With regards to how to start the process thats i dont know. Check both CRNPEI and CNO, you need to be assessed first by NNAS for comparability,,how many gaps you have. So prepare a good and detailed job description and just ask your manager to sign , not the one from your company as its usually a general/broad JD. I think gaps score also depends on your JD. I know someone just submitted the one from their company and she has a high gap score that needs to fill in( the lower the gap the better), some takes an online study to fill in these gaps
First things first, let your credentials be assessed by WES or any other accredited intitutions and take the ielts, if you havent done yet. Then create an ircc profile then pei profile.
God bless to your application