Assuming the price is right, the best time to sell is when you feel you’ve taken it as far as you can take it. Even if the business itself has potential beyond that.

If you sell earlier than that, then you could leave huge amounts of money on the table given the way businesses are valued as a multiple of profit; For example sometimes 100k profit growth could yield 300k - 1m in additional valuation. This mentality is why Zuckerberg didn’t sell Facebook to Yahoo! for $1bn.

On the flip side, if you don’t sell at the peak point of how far you can take it then you may risk fortunes turning, company going backward, and receiving a lower valuation in the future.

So do you feel you’ve taken it as far as you can? And, is continuing to Captain the ship something you can and want to do?

Honestly, age aside, given what you are doing I’d probably keep it aside for working capital (think of it like an emergency fund for your day to day business spending).

Index investments etc are ways to keep wealth and potentially grow it over time. But it’s not a way to earn money quickly unless you are very lucky. They are good to learn about, and index investing subjectively good advice that entrepreneurs often do with their wealth, but index investing is not entrepreneurship.

So if your goal is to be an entrepreneur, then the entrepreneurial thing to do is to use that capital to help you with your business.

Other ways to spend it:

1. Marketing (start small, test, spend more once you found a channel that work)
2. Equipment. E.g. Could a new computer help you to be more effective?
3. Self learning. E.g. could a $200 online leadership course or $20 Masterclass subscription help you to be more effective.
4. Graphic design to improve your small business branding and make you come across more pro.