How do you incentivize your users for user research?

Hi Hackers.

I managed to get around 100 emails for my product and I sent a welcome email to all the users asking them to schedule a 30-min 1-on-1 session. I wanted to ask them a couple of questions but also to walk them through the prototype and the features. 3 out of 100 users scheduled a meeting, but none actually showed up :/

Now I'm trying to analyze what I did wrong. Now, I know 100 people is not a lot and this is a numbers game, but I'm assuming that If I would somehow incentivize users for interviews, the response would be better. I was thinking to offer X-months of subscription for free, but I'm not sure if that's enough since the product is not launched yet.

How do you incentivize? I'd love to hear your thoughts.