'timestamp_sdt' for counting from zero hours of a specific day
<?php
echo $timestamp_sdt = strtotime(date('d.m.Y',time()).'00.00.00')*1000; echo '<br><br>';
echo date('d.m.Y H.i.s', $timestamp_sdt/1000); echo '<br><br>';
?>
will give out:
1734649200000
20.12.2024 00.00.00