Answer is - Depends!
Depends on which talent you are looking for.
Let me elaborate.
Some broad guidelines -
0-6 years - mathematical abilities, physical (sports, dance) abilities and public performance abilities can be seen by beginning of school.
Interest in music and some talent becomes visible by this age.
Though one MUST remember that such early signs are no guarantee of lifelong pursuit.
Some exceptionally gifted children start demonstrating self learning and "connecting the dots" at this stage.
Ability of a child to crack code of indian school exams and score 90%+ marks is not a reliable sign of anything other than academic success in middle school.
Social skill is excellent ability that takes one places no matter which field is chosen.
Language learning ability
Verbal descriptive language ability
Language teaching ability
These are all different in their own right.
None of these are really valued or nurtured in Indian school system. So children with these interests really suffer badly in our schools.
Almost none of them are apparent in school, even in grad school hence surprise successes appear at reunions.
NO psychometry test can tell you this.
This should be obvious to common sense of a loving, observant parent.
Do you really believe that such future predictions about job and market are really possible? If you or anyone has that ability, you should be a billionaire by now anyway.