I think. the ideal age would be when you are 27-28 years old.
As per my observation among friends and colleagues, they have at least one child by the age between 30-32.
so, if we calculate, by the age of:
16 y/o can complete SEE/SLC,
18 y/o can complete +2/higher secondary
22 y/o can complete bachelors degree ....join internships, full time jobs, side hustles start earning.
24 y/o can complete Masters degree .. have permanent jobs, or enterprise.
Therefore, imagine someone is getting married at 28, and have kid(s) by 30, parents at the age of 58+ can be able to see their kid(s) have stable life by 30's.
it's just my logic only. But the things with others life could be different.
There are examples within that one gets married early because of the family pressure. Honestly, they are also doing far better at the moment.