As already mentioned, good is a relative term. Against my normal group of friends and or those who taught me the sport as a fun diversion to do after work? Maybe a year. (2006)
Just winning a tournament? That was four years in, and that was in Intermediate. (2009)
Throwing competitive distance? Again, four years where one day it magically clicked with a Star Wraith where I instantly went from 300 to 375 - side note: whatever I did where it suddenly clicked, it occurred between rounds and completely threw off how I would play that course.
Being competitive as a top amateur? 10 years. I still have long and painful stretches where nothing is working correctly, but I know that on an average day I can hang in my division. On a good to great day, I should hang around near the top. I had a really good 2018 winning two big tournaments.
All that being said, there is a plateau that was reached, and I cannot ascend from good to great. It was nearly 10 years ago that I jumped from 300 to 375. I am 43 now versus 33 then, but through technique I have been able to maintain an average max of 400 - ranging from 380 to 430. Nothing I have done can get me over that hump for more distance. As for putting, nothing has ever worked and has always been the Achilles Heel of my game. Practice at home has never translated to the course. So, I am good, but I do not think I will ever cross over to great and be able to hang in the Open Division, age-protected or not.