What the best time to to seek funding of your business?

Why is "only when you really need it" missing from the list?

It is important to understand to entire point of funding a company, which is to give (just) enough runway for a good idea to land. A round of funding ideally SHOULD feel like a dual-edged sword: you give up something valuable (equity) at a price that should feels like a bargain/calculated risk for whoever funds it AND feels a little painful for you to part with. That means it is a fair bargain. Funding is not the goal, it is a calculated strategy like dumping fuel to help your plane land safely!

"When you need money to grow".... Hmm that option is not there! Which means you may never need it if you have a sustainable business.

The best time to seek funding is when you can easily raise. The only way to see if you can easily raise is to try. Obviously the closer you are to product-market fit, the better.