mine still had a lot more of adjustment to go. You will start to feel it get notchy, especially at slow speed when you take off from a stop. Mine could have gone another 10k miles based upon stretch. I don't like notchy chains. You can also examine each link and see if you have a frozen link. I had a couple.I'm right at 14000 on mine. I'm not sure how to tell when you need one other than when it stretches so far you can't adjust it.
If you chain is quiet and not notchy, keep riding with that big grin on your face