Just launched, made it free to use until I see more traction, got about 20 registered users.
Is it a good time to ask them for feedback ?
What feedback should I be aiming to get?
What questions should I ask?
What questions do you use in the early days of a product?
I think you can gather feedback when you validate your idea.
Asking specific questions can be a bit difficult. In https://seodity.com we approached the case in such a way that we try to get as many users as possible.
We see if they come back and how often. In this way, we can measure their satisfaction in some ways.
Additionally, we will use https://www.upvoty.com/ to collect user ideas.