How early in your product's life should you actually niche down?

It's weird having a decent number of active users while having zero clue what your typical customer actually looks like. Some people log in every single day for work while others signed up months ago and completely vanished. Trying to build features for a mixed crowd like that makes roadmaping really tough because you can't please everyone at once.

If you've been through this stage, at what point did you decide to narrow down your target market instead of trying to appeal to everyone?