There are many ways to do a track plan. Some folks like computer cad programs and some, like me, simply draw the plan with a pencil. In my decade of model railroading I've come across guys that are into year two on their 'cad' plan! Some are in year two with their pencil plan. I have a layout built and torn down in two years. Not that they are wrong however. The way we spend our time is a personal thing but I fear many of these "long term" planners may be afraid to finished their plan and get to the next step.
After I pencil in my track plan, usually a less than 10 minute job, I draw out the plan and rough scenery ideas on the 'plan' paper that you've seen. This paper is my map and I will try, but not always succeed, in adhering to it. The first thing I do before any building is to buy the approximate amount of curved track I will need. I then solder all the curved pieces together. Hiding the soldering on the inside of the loop of course. Then I layout the curves out on the bench work to see if they fit. Like this:
When I see that all the curves will fit I put all the curves away until I need them. I do it this way because I know they will fit and when it comes time to build the subroadbed I will have the curves as templates. No guessing during the subroadbed building stage. This, to me, is a critical sequence in building layouts more quickly. Jim