How soon is too soon?

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I want to put somewhere in the blurb or title that volume 1 is finished with writing and volume 2 is being worked on.

But I've still got a bunch of chapters scheduled till the end.

I don't want to make readers think they are days away from the end.

But I've heard mixed messages.

Some say they are more likely to begun reading when they see that, some might wait even longer until 2 comes out before they even try.

So do I just wait until the last chapter eventually drops and let the readers know the progress at that point? Or give the heads up early that there's more coming already?

Trying to find the best medium between trailers and not spoilers.

Thoughts?