Calculation is feasible and quite easy. But, the simplest way is to wait and see - you will notice it
- when the average tumbles in giant steps (as old bad scores are kicked out);
- when the average drops from scores higher than the average (same reason).
Also, in most cases, this is only half of the story, as players have to push the average down to 60.000 for further promotion. This is a long grind!
Thus, the most important thing is to stay happy, to have fun in the game and to practice by playing. Then, success will come!!