After discovering my steek mistake, I wound up just ripping back the 2 or 3 rows I had completed and then binding off the last BO stitch and starting the steeks again. I actually had two different colors connected to the sleeve edge, and I just felt that it was easier to do it right than to try to salvage a few rows.
I've completed all of the decreases, and since I'm a tight knitter and making the smallest size, I'm finding that I almost wish I had a smaller circ for this part--I'm having to push and pull my work over a lot since there are barely enough stitches for it to be workable on these needles. On the plus side, all the pulling on stitches is actually having the one side benefit of somehow evening out my tension!
I've completed about 4", so only 3 1/2" more to go! While I got stitch gauge, I'm finding that I didn't quite end up with row gauge, so that, combined with knittting an additional 1" before establishing the steeks to make sure I wound up with a true empire waist and not bisected boobs like Interweave's model, means that I'm ending up with more repeats of the pattern than I would otherwise.
I'm so close, and can't wait to finish this beautiful sweater! Below is a picture of my progress since establishing the steeks: