Enterprise founders: When does customer interest become real validation?

I've been building enterprise software, and one of the harder lessons I'm learning is that a positive conversation doesn't necessarily mean you're closer to a customer.

I've spoken with leaders who recognize the problem we're addressing, can describe how it affects their teams, and are interested in seeing a solution.

But interest and adoption are two different things.

In enterprise environments, the person experiencing the problem may not control the budget. Even when there's a potential business case, there can be questions about implementation, security, organizational readiness, and competing priorities.

It's changing how I think about validating enterprise software.

I'm learning to distinguish between someone agreeing that a problem exists and someone being willing to commit time, resources, or budget to solving it.

For founders who've been through this, what was the first concrete signal that told you a potential enterprise customer was genuinely ready to move forward?

Was it agreeing to a pilot, introducing you to the budget owner, allocating internal resources, or something else?

I'd love to learn from actual experiences, especially what you initially mistook for buying interest.