When do you actually need to put in a distributed tracing system

Hey everyone, I'm trying to figure out when it makes sense to add distributed tracing to our systems. We're getting bigger, and our services are getting more complicated, so debugging stuff across them is becoming a real headache. When did you guys start needing tracing? What were the big signs that told you it was time to spend money on tools like Jaeger or Zipkin? Any tips on what to watch out for before we dive in?