hhhhh
Time between average & GM

10,000 hours of study. If you study 4 hours a day x 5 days a week that’s nearly 10 years. Even then that’s only if you study the right material and play sufficiently strong competition. Even then you might not make it.

I've heard that Malcolm Gladwell 10,000 hours figure. It sounds clever, but it doesn't really hold up under examination. It takes both hard work AND talent; your personal mileage may vary depending on how much of the latter you have.

i would say it is entirely up to you. how bad do u really want it?
just as anything else u might want in life....

If you win the World Senior Championship, you are awarded the grandmaster title. Janis Klovans did this when he was 62.
Another approach is to give so much to chess that you are awarded an honorary GM title such as George Koltanowski was when he was 85 or Arnold Denker was when he was 67. Forty years writing chess columns, giving simuls and playing in and organizing international tournaments would set you well on your way I guess.
In the past I had asked how long it would take me to become a Grand Master. I was told that I was already too old, even though I was a teenager at the time. Nearly 10 years later, I still get adrenalin and excitement out of chess and that's all that should matter.
I can't help but wonder how long it had taken other Grand Masters to reach their level. What sort of effort does it really take and over what (if any), 'typical' time frame?