Your proof is your copy of the COPR. When you get your COPR in the mail, you get two copies. You give both to immigration officials when you officially land. The first copy with your picture on it is kept by officials. The second copy is returned to you and this is your copy to keep. This is proof of your landing and that you became a PR on the date written on the COPR. Your copy of the COPR is very important. Keep it safe. You can use it to apply for provincial health insurance. You need it when you apply for citizenship. You need it to collect your pension. It is your proof of when you became a PR.