From the December 1967 issue of Popular Science, page 72, in an article about the tech of Star Trek:
What year and model was it?
In the early 1960s, network radio and TV started using automated equipment to notify stations of programming or news announcements. Originally, the equipment was triggered by clicks like a rotary phone, but they quickly went to electronic beeps like this.
Green and Red LED calculators replaced pixie-tube calculators, but I can’t remember that any of them beeped.
The beeping watches were LCD, not LED. LED displays burned a lot more power, and LED watches were almost entirely non-existent.
BTW, in 1981 obviously a lot of kids got an LCD watch for Christmas: some of them turned up for their first university lectures in February (Southern Hemisphere), and in a lecture theatre of 150 people, their watches started beeping around 10:00 (lectures ran 9:15 - 10:15). By the next day, anybody who’d had their watch set to chime on the hour had turned that feature off.
Actually, vacuum fluorescent displays replaced nixie tubes in 1967. By the '80s, hundreds of millions of VFD calculators were being sold annually.
Well, I had one in like 1975. You had to push a button to get the time, because, as you note, they sucked power. I miss it, it was a good watch, with 70s styling.