If you're trying for eligibility based on work permit, the requirement is full-time employment for six months, c.f. the Ontario government website:
- are in Ontario on a valid work permit and are working full-time in Ontario, for an Ontario employer, for at least six months
My ServiceOntario office was asking for a letter from my employer and gave me a template for this. According to this wording of this template, you didn't have to have already been working for six months, the employer just needed to attest that you would be employed at least six months. (Don't know if they have a standard, province-wide template letter.)
My difficulty was that I'm self-employed. I just launched my sole proprietorship, a consultancy, and could only claim perhaps half-time employment. Which did not qualify me. The agent was quite strict on this point (and rather unfriendly, as if I were trying to scam OHIP).
So I ended up waiting for the approval of eligibility letter from IRCC, which thankfully came the next week. So now am approved for OHIP but coverage won't start until after the three month waiting period.
All very frustrating as one extends and further extends rather expensive travel insurance coverage. The more so given that the info we received before deciding to move to Canada was that I would be eligible once I got the work permit. And that the waiting period would be counted from when I established residency. Bref...