Non disclosure agreement for concierge early adopters?

I want to be extra careful and publish my first MVP to a concierge early adopter. I would like to know if it is common to ask her to sign a non disclosure agreement.

In my experience it's not common - and most startups dramatically overestimate the danger of letting other people know what their idea is. Products very, very rarely win by being first to market. They win by being best. That's something that's driven by the company - not the idea.

It's sometimes hard to discover those initial users to help you validate product/market fit. Adding another barrier to folk using your MVP seem sub-optimal.

I am not certain if it is common. But it's always a good idea to have an NDA between parties before publishing your MVP.

EDIT:
Some web applications also add a legal content page that explains the "Early Experience Terms of use". This might also be sufficient.