The decision, and how it is usually made
Most people make this decision on mood. A bad quarter at work, a friend who seems to be doing well, a redundancy, a good idea at eleven at night.
None of those are bad reasons to start thinking about it. They are poor reasons to decide, because they say more about the week you have had than about the working life you are built for.
A kundli cannot tell you whether a business idea will succeed. What it can describe is which of the two working lives your chart actually supports, which is a narrower claim and a more useful one, because most people making this decision have never seriously considered that the question has an answer.
Two planets, not one house
The standard approach reads the 10th house. In Bhrigu Nandi Nadi (BNN) the 10th is an output rather than a starting point, and for this particular question two planets do the work.
Saturn carries duty, structure and the long accumulation of a career. It describes tolerance for hierarchy and process, and reward that arrives steadily rather than in bursts. Saturn is the shape of employment.
Mercury carries trade, calculation, negotiation and exchange. Buying, selling, pricing, the conversation that closes a deal, the arithmetic that tells you whether the month worked. Mercury is the shape of business, because a business is a machine for repeated transactions.
Saturn vs Mercury takes that distinction in depth. The short version is that the answer lies in which one dominates and how the two relate.
The four readings
Saturn strong, Mercury quiet. Employment suits. This person builds well inside a structure and is often excellent at the parts of work that others avoid. In business they tend to create something that runs entirely on their own effort and never becomes an asset.
Mercury strong, Saturn quiet. Commerce suits and hierarchy chafes. Deals happen, movement happens, and the risk is that not enough structure gets built underneath to hold any of it.
Both strong. The genuinely commercial combination. Mercury finds the transaction, Saturn builds what survives it. Worth saying plainly: this is also the chart of someone who does very well running a commercial function inside a large business, which is a legitimate outcome rather than a compromise.
Both quiet. The professional chain runs through Jupiter instead, which points at advisory work, expertise and guidance. Plenty of excellent careers sit here, and the job-or-business framing simply describes them badly.
What the chart says about the risk
There is a second, more practical layer, and it is the one that decides whether a business survives its first two years.
The connection between the 2nd and 12th houses, income against outflow, describes whether money that comes in stays. A person with a strong commercial chart and a heavy 2nd-to-12th connection will generate revenue and not retain it, which in a business is considerably more dangerous than in a salary, because a salary has a floor and a business does not.
Knowing that in advance changes what you build. It argues for reserves, for someone else holding the books, and against the expansion that feels obvious in a good quarter. Why does money come into my business but never stay deals with the pattern specifically.
Timing is a separate question
Aptitude and timing are two readings and people routinely collapse them.
Which suits you is read from structure, which does not change. When to move is read from yatra, the journey of the slow planets through the chart, which does. A supported period and an unsupported one produce very different first two years from the same decision and the same person.
Business kab start karna chahiye covers the timing side.
What honest advice sounds like here
It does not tell you to follow your dreams and it does not tell you to stay safe. Both are slogans rather than readings.
It says which of the two your chart is built for, what the specific risk is in your case, whether the current period supports a change, and what you would need to put in place to compensate for whatever your chart does not carry. That last part is the most practical output of all: a person weak on Saturn does not need to abandon business, they need someone in the operation who is not.
And it does not evaluate your business plan. If a reader offers to tell you whether your idea will work, they have moved well past what a chart contains.
Where to go next
If you have decided on business and want to know what kind, which business is best for me reads Mercury's condition and its bonds.
If you are still weighing the two and want the underlying method, Saturn vs Mercury is the fuller treatment.
A money and profession reading takes both planets together and checks them against the work you have already done, including the ventures that did not work. Those are the most informative data points you have, and almost nobody brings them.