Thank you all very much. This helped me reconceptualize what I was doing. I made an excel spreadsheet of the pattern went back 10 rows in the pattern from the shoulder start, then measure to get my gauge which told me I needed to back off another 1.5 inches from where I was with the back. Sounds like a complicated way to get to where I need to be! Fortunately this is a simple stockinet, without any pattern to it. Part of the challenge of knitting is figuring these things out!