What will be the most accurate halving time

Very difficult to predict at minute-level (let alone at second-level).
This is due to the nature of the code, and its interaction with millions of miners worldwide. This introduces stochastic elements (randomness) into the process, thus making it virtually impossible to accurately predict the time of the halvings.
Here's an article by CoinDesk explaining why it's so difficult to predict:
CoinDesk Why Bitcoin Halving Calculators Are Out of SyncHere are 6 halving timestamp estimates, from various places on the net (sources not important to mention):
Saturday, 20 April 2024, 03:26:00 UTC
Saturday, 20 April 2024, 05:11:11 UTC
Saturday, 20 April 2024, 06:26:00 GMT+3
Saturday, 20 April 2024, 05:12:00 GMT+3
Saturday, 20 April 2024, 05:03:00 CET
Saturday, 20 April 2024, 01:22:50 UTC
Based on the above, I guess we should be expecting it sometime...
[UK/Europe] In the early hours of Saturday, 20 April 2024.
[USA] In the late hours of Friday, 19 April 2024.