“I don’t know yet” is a braver answer than a confident guess.

Confidence is easy to produce and hard to retract, which is why so many guesses get delivered as facts. Admitting you do not know is the more exposed position, since it gives up the appearance of competence right then. It is also the more useful one, because everybody can now act on the real state of things instead of an invented certainty.

Use it once this week where you would normally reach for a guess. I am not sure, let me find out. Then actually find out and come back, because the phrase only holds value if the second half arrives.