when to ditch polling for push notifications in microservices?

I'm working on a distributed system where different services need to react to changes in other services. Right now, a lot of it is based on polling. For example, Service A polls Service B every 30 seconds to see if its data has changed. This feels inefficient and can lead to delays. I've been thinking about moving towards a push-based model, maybe using message queues. What are your thoughts on when it's worth the effort to switch from polling to a push/event-driven architecture? What are the trade-offs you've seen in practice?