1 week to launch but waitlist isn't filling: delay until critical mass or ship now?

My product is UGC (user-generated content). Users create decision posts and the community votes on each other's decisions. So I figured a certain level of critical mass needs to be there from early on for the effect to actually kick in. That's why I built a waitlist: the strategy was to have people enter together as much as possible so some interaction can happen from the start.

But the waitlist isn't filling up nearly as much as I expected. To be fair, it's been less than 2 weeks since I started promoting.

The problem is, there's only about 1 week left until the announced launch date. Since it's UGC, would it be right to push back the launch, or change it from a specific date to a specific-number-of-signups threshold? Or, since that's realistically too hard, would it be right to launch on time anyway, let even a few people use it directly, and just go through the feedback loop fast?

There's also a concern: would feedback from people who only experienced the product without interacting with other users really be meaningful?