When I first bought a French press, the instructions said to pour hot but not boiling water over the coffee. They were emphatic about what the temperature should not be, but vague about what it should be. (Boiling water extracts oils that you’d rather leave in the grounds; water a little cooler brings out just the oils you want.)
I asked someone online — sorry, I don’t remember who — and he said that after your water boils, set the kettle off the burner and check your mail. When you come back, the water should be at the right temperature. That turned out to be good advice.
I don’t know whether he meant postal mail or email, but it doesn’t make much difference. Unless you get caught in replying to email and come back to room-temperature water.
Now if you really wanted to geek out on this, you could use Newton’s law of cooling along with the surface area, thickness, and material composition of your kettle to compute the time to let your water cool to 200 °F (93 °C). You could assume a kettle is a half sphere …
Related post: A childhood question about heat