Every 210,000 blocks, the block reward for the miner is halved. A block is found about every 10 minutes, from this you can roughly calculate when the halving takes place. As of now it is less than 1 year. There are different countdowns, but April 2024 is likely. The last halving was in May 2020. The block reward was then halved from 12.5 to 6.25 Bitcoin. The upcoming reward will then be reduced from 6.25 to 3.125 bitcoin.

An idea for a new guessing game: guess the date and time of the first block of the halving.