Unfortunately, I didn't take a before picture of my back. But I'd say it was moderate cystic acne. I didn't have a ton of cysts everywhere, but I would have about 4 to 5 big, painful ones on my back and shoulders. It got to a point where I would be really ashamed to wear tank tops or go swimming. But now, there are just a couple red spots, no pain, and acne is almost nonexistent.
It seemed to me like my back was the first to clear, but it's different for everybody. My initial breakout was terrible, including on my back. I would say that I probably started recovering from the IB around 2 or 3 months and have been actually clearing since then.