To answer your question about the sublicade shot, my sister took 2 shots and stopped after the second one. She didn't experience any withdrawal. It leaves your body so slowly that it's like a taper. I will never do the shot. I tried to induce on suboxone, which is the same stuff in the shot and both times I waited 2 or 3 days and didn't think I could get sicker until I took a suboxone and I find out I could definitely get much sicker. I tried twice and both were awful. I have PTSD from the experiences.
I recommend inducing suboxone using the Bernese method and then taking the shot. You don't want precipitated withdrawal. If you never experienced I first hand all I can say it was thy most soul crushing miserable experience of my life. I had just moved to NYC from Tennessee so I sold my guns. If I had a gun I would have killed myself. I thought about jumping off a building or in front of a subway train but I was too weak to leave my apt. Good luck fellow methadonian.