Doing the walls next spring, so just planning at this point. I'm unsure whether building the walls out will be worthwhile compared with just dense packed cellulose in existing 2x4 walls. My labor is at no dollar cost and I buy materials on sale, so I can really keep cost down compared to hiring a contractor. It just takes longer working a few hours in the evening and weekends.
As I approach actual construction, I'll begin noting progress in this thread.