In general in Indonesia, until the age of 5 years, children are free to play, age 6 years start studying at school, starting from kindergarten to high school / vocational school, at the age of 17 or 18 years, finish school, if you want to continue then generally 21 years finish college and just start working or doing business.
Some work or trade while still in school, meaning they have started earning money from the results of their business. When you finish school or college, you already have provisions, whether you want to work or want to do business.
Some of them think that school is nothing, the most important thing is to be able to make money, as a result, since childhood, they have been looking for money, until adulthood they continue to make money, maybe even their business becomes big and advanced, can support many people and send many children to school.
And there are many other versions of one's life, between work, business and school, which obviously humans cannot escape the name of property, clothing, food and shelter, are basic human needs that require possessions.
What is unique then for a Muslim, having an Apostle who is a businessman, but that does not mean never being a worker, from the life of the Prophet it can be known what age and under what conditions someone deserves to start becoming an entrepreneur.
Rasulullah
The Prophet Sallallahu alaihi wasallam, at the age of 8 years already received wages from his work as a goat herder. At the age of 12 years has been invited to trade by his uncle Abu Talib, unmitigated, the age of children now who have just entered junior high school has learned to trade, to a very far place, namely to the Levant, or to the territory of Syria, Lebanon, and Jordan.
No wonder then the age of 17 years to 20 years the Prophet Sallallahu alaihi wasallam has been able to compete with big businessmen. But what is of note is the Prophet Sallallahu alaihi wasallam, known as a businessman who is good at counting, honest and professional.
One more thing to note, that the trader is an entrepreneur, is not separated from the broader dichotomy of entrepreneurs from traders. The Prophet Sallallahu alaihi wasallam had a lot of knowledge, which is now known as the field of Muamalah Maliyah, which is much broader than economics, then the merchant is a businessman, yes an economist too, the point is that a Muslim is so extraordinary, because the Prophet as an example is so extraordinary.
Again, the Prophet then at the age of 25 years married Siti Khadijah Radhiyallahu anha who was 40 years old, a businessman too, husband and wife businessman!, husband and wife cooperated mutually beneficially, and harmonious and romantic relationships, sacrificed each other!, even though both were businessmen.
Marriage made the Prophet an even greater businessman, with larger expeditions, import-export on a large scale. But remember that at that time the Prophet was known as a person who shiddiq (true), amanah (trustworthy), fathanah (intelligent), and tablighi (conveyed).
Closing
The author is very likely wrong when entering the concluding section, but let the author want to say that, educate children as well as possible with Islam so that their morals and knowledge Masya Allah, and introduce them to the world of business / work or property, as early as possible at least 8 years old, then become serious at the age of 12 years or at puberty, and mature, free in a positive sense at least at the age of 17 years, and marry or let marry at least at the age of 25, hopefully at the age of 40 will become a true Muslim businessman. Aaamiiin
If it is too late, then fix it as best you can.
Wallahu a'lam bishawab