It's a single KLUNK and then all is fine. Even when I'm at a slow roll and accelerate no noise. Just from a dead stop. Already orderedIf it's one "clunk", it's probably not chain replacement time.
If it's a series of "clunks" that go away when you are moving at 15+ mph or so, it may well be your chain.
25k is pretty good mileage for a chain, IMO. I don't do that well.