I just did some quick analysis of the March FIDE Ratings List for players in India.
There are over 40,000 players from India listed, topping the list. (Russia has 39,000.)
Looking at the distribution of birth years, the peak is 2004 and the highest portion of the curve is for players born between 1994 and 2011, so those would be players who are in the age range of 13-30.
By contrast, US Chess memberships by age (and probably ratings by age as well) peak at age 10 and tail off dramatically after age 13.
From this I would infer that most players in India are not playing in FIDE rated events until they are teenagers, but whether they’re playing in other (non-FIDE rated) events when they are younger is not something this data would tell us.
Graphically it is very interesting, but keep in mind India’s total population is about 4.2 times the size of the USA.
