Hello, thanks for ordering the book! Not sure if anyone has broken it down into watches, though I believe Yochai Gal has said that he Cairn-ified the map. I don't think he's posted that anywhere, however.
But here's our method, which is pretty simple, and uses the map scale, and the assumption that people on foot can travel up to 24 miles per day (or 36 miles on roads). A useful visual is that it's about 30 miles between Cimbrine and Fort Flumenel, so call that a distance of 3 watches. With that as a reference, you can eye most any other distance on the map. The majority of distances between locations are therefore 1, 2, or 3 watches.
I hope that's helpful, and that you have a blast playing it with your family!