I have only studied the map a bit, but what a neat thing to look at. I won't speculate on time, and of course, it was a working map used over several months. (surprised someone never tore it on a tree or fell in the mud. Yeah, maybe architecture has changed in 100 years, but that's what probably would have happened if I was carrying it around!
Two things strike me - he repeatedly called out those 5-6 holes, but was vague about the coast holes, other than he would have them. Those six holes are designed in the most detail, while 1 and 18, maybe 2, don't even have clearly established centerlines. It is clear he designed the course out from those six holes (again, all in the middle of the property)
Second, I notice a yellow line around the border near the first tee that later was bought for the pro shop. It appears that border troubled him somehow, as he noted it. BTW, someone asked where that first pro shop was located, and the rendering in SG shows it just right of the first tee.
The maps do show different holes in various states. The bunkers drawn in yellow pencil look pretty close on holes 3-9, most with additions later, but little on 10 (although two cross bunkers there look to still be in place) and 12-13. Not much on 15-18, or 1-2. In general, it seems more bunkers got added later, and fairway bunkering is closer to the plan than what the greens ended up. For example, 9 green shows ringed with 5 bunkers, and seems to have ended up with less (looking at the SG rendering.)
It does show the whole process was far from linear in CBM's mind, with some holes close to final designs while others haven't even been finally routed. I think that suggests it will be hard to pinpoint what was done when, although, an initial date on the plan would help.
It fascinates me, and I have some thoughts, but I won't share them, as I will surely be shot down as a moron.
Let's just hope the intrepid researchers keep coming up with new stuff.