Will landing paper & passport be sufficient for OHIP eligibility upon arrival? The answer is No, although there is no waiting of 3 months, they will need three documents to apply for OHIP.
1. COPR
2. Address proof
3. ID Proof/Passport
Even if you open their bank account and get the bank summary the same day, as proof of residency, it will not work. You have to wait for an actual monthly statement that will deliver to your mail.
Check this link for list of documents required:
https://www.forms.ssb.gov.on.ca/mbs/ssb/forms/ssbforms.nsf/GetFileAttach/014-9998E-82~5/$File/9998-82E.pdf
Pro tip:
Get a lease agreement set up in their name, this is the fastest method that I have used.