I didn't really get anything until I went for pre-admission a few days before my original surgery date (I subsequently got "bumped"). Essentially it was a half day session where they did all the administrative stuff, they had an orientation session (several OHS patients) to give pre-op and post-op instructions and watch videos, and I met individually with members of the surgical team.
Before that, the hospital just sent me a notice in the mail of when and where to go for the pre-admission. That said, they mentioned their website in the letter "for more information", and there I found pdfs and downloadable videos of pre-op and post-op information for OHS patients. It was the same stuff they ultimately handed out, or we viewed, at the pre-admission session.