Number of yrs. to reach the finished line?

Finish line! There ain't no stinkin finish line!
There I said it, I have been at this for 35 plus years and have yet to see a finish line. You do get pit stops, some long ones a few years and some short ones only a few months but that is all. The never ending search, that's the fun of the trip. For me anyway.

It has taken me six years of effort to cludge my system together to the point of complete satisfaction. (I still wish to install dedicated lines but that is for completeness rather than seeking out audio improvement.) During the journey, never having excess money seemed to cause great frustration for me as I knew what direction in sound to continue to improve towards but could not get there fast enough. But looking back on it now I feel it was a blessing as it forced me to do far more investigation and be very disciplined with my selection process. Limited funds kept me from purchasing "flavor of the month" gear and instead forced me to rely more on my own ears than others' opinions. I still lost some money on some of the items I've replaced over the years but each replacement was always a great improvement towards the sound I was chasing.

40 years in the hobby and I think I'll be looking for a new preamp at my funeral.

The 'end' you think, but I've been at this for over fifty years and there is no end, but the grave. Looking forward to heaven, when music will be endless.

Gotta say, I have no current plans for major changes. I have owned the Aerial 9's for about 5 years, Lector for 3 yrs. and Tom Evans Vibe/Pulse for 3 years (off and on - I have owned several of them). I have only had my Clayton amps about a year, but with the upgrade to current product, I cannot imagine wanting different amps. The only possible near-future changes I foresee would be with my source, where I am currently going between the Lector and a MUSE, and also by potentially adding server based music.

To get here required some stops, starts and sideways moves to try new things which usually were not aligned with my sonic preferences. I have found simpler to be better for me, by staying mostly away from tubes, simplifying support options with Herbie's products, and getting off the cable merry-go-round. In summary, I will not say I am totally done forever but, for now, I will move forward at a much slower pace since my current system sounds great to me, I am a little tired of the upgrade process, and I have other ways I would prefer to spend my time. To answer the OP question, I started upgrading my previous system of 15 years around 1999, so it has taken 12 years to achieve my current system.