There is no waiting period right now:
The 153 days after residency means this: you are eligible to be covered if you have settled in Ontario and WILL reside in Ontario for the 153 days after settling. If you are arriving to just do a soft landing, you are not eligible, according to
Mobe reviews.. If your'e coming for three months before you move to some other province - not eligible. Etc.
If you get OHIP coverage and get treated and then don't reside in the province per the requirements above, they CAN go after you to reimburse amounts spent. I have no idea how frequently they do this, but they can and they do sometimes.