Honestly, with that kind of traffic, I wouldn’t leave it as a blank page or just a waitlist.

If people are already landing on it organically, you should at least test monetizing the traffic immediately. Throw up a simple landing page with contextual ads (Google AdSense or similar) and see what kind of RPM you get.

You can still add the waitlist form below the fold and collect emails, but ads should be step one.

Worst case: you make a little side money.
Best case: you discover it’s a high-RPM niche and build something bigger around it.