Marking the dips with thread worked! I managed to correctly tat the first time through, and I'm very happy about that!
I took my 112" scarf to school today to get opinions about the length. We have three new teachers in our building this year, and I call them my scarf girls as they each wear scarves almost every day. They each tried the scarf on and showed me ways to wear it, so I do feel confident about making long scarves now. In fact, I started another one right after school!