Ask HN: How did you found your niche

Been struggling for a while with getting my first customers for my side-project, that I find very useful regarding data science. I would like to ask you a couple of questions for finding a niche: * How your searching did look like? Google? Local hackerspaces? * How long did it take till you realized that >it was your niche<? * Have you been engaged with the community before you started to market your product?