when to introduce message queues, dont wait too long.

So, I've been thinking a lot about system design lately, and one pattern that keeps popping up is message queues. We've all seen them used for things like background jobs or decoupling services. But when's the right time to actually add one to your architecture? Are there specific metrics or situations where it's a clear win, instead of just adding complexity for no good reason? Really curious to hear what you all think and what you've experienced.