I would like to add to this post to give some you an idea. I just did my landing and the procedure itself took no more than 5 min.
My background: I was an in-land applicant as I am a temporary worker in Canada. My country of citizenship is visa-exempt (meaning that a tourist visa is not required for us entering Canada).
My landing: When I reached customs (Toronto airport; around 9.30 pm) and provided my passport the officer let me pass pretty much immediately, before I had the chance to explain my 'landing' or even show my valid work permit. I then explained that I am a temporary worker and I have my CoPR with me and I would like to 'land' as a PR - I was then told to proceed to the immigration room (which is within the same area). This room had no waiting line; virtually no-one was there apart from a few people sitting down (probably waiting for an actual interview of some sort). The officer took me straight away. I again mentioned my intention, gave him the CoPR copies (copy for them and a client copy) and my passport. He asked me if I have been convicted of any crimes, married, and have children. Once that was cleared he filled in both forms, I signed at the places that he indicated and he then stamped my passport page and wrote an ID number. He kept his CoPR copy and returned mine. He then said that his copy will go for PR card processing. And that's it, the 'landing' ended.
I asked him about leaving Canada and returning while waiting for my initial PR card. He stated that while a travel document should given to them upon entry, being from a visa-exempt country will pose no issue.
Hope this helps!