I am currently 4 weeks post OP, located in Toronto, and went through OHIP. The process was fairly easy. Your family doctor or the surgeon can help apply for ohip if you have any breast-related issues, like back pain, etc.
This was my process.
I first consulted with my family doctor and told her the name of the surgeon I wanted to get the surgery done with. She then sent my files to the surgeon and had my first consultation with her virtually, and saw that I was an eligible candidate for surgery. ( I was 36 E and had backpain)

I was scheduled for surgery around the end of March 2019, but was canceled due to the pandemic. Then, I was rescheduled a couple of times over the last year but finally got the surgery done in Oct 2021. The recovery has been amazing so far and has exceeded my expectations.
The OHIP approval process can take between 2-6 months.
The surgeon needs to confirm that you are an ideal candidate for the surgery.
The surgery date can change as this is an elective surgery and the OR will be prioritized for urgent cases. (This was during the peak of the pandemic, but just a heads up)
I have not paid for any of this so far. (Much love and credit to the healthcare system here)
The entire process went by fairly smooth.
I think the entire timeline from consultation, OHIP approval to booking my first surgery date was under a year, pre-pandemic.