You're not going to get one.

You reach out every few months with updates, especially if those updates include the KPIs they're looking for to invest. If you don't know what those KPIs are, then your initial conversation with them was too hand-wavy.

If you have traction and you continue to gain traction, follow up every few months with a "This is where we are" email, if you'd like. But if you're waiting for them to do something before you make whatever move you were going to make after they made their decision, you're going to be waiting for a long time.

Slowly move on. Best if you can get interest from another investor. One common reply from investors is "we want to see more traction" (number of users, pageviews, engagement etc) which I'd translate to "we want to see (consistent) growth first"