Countdown.php

См. документацию.

<?php
 
namespace Bitrix\Landing;
 
class Countdown
{
    public static function getTimestamp(): int
    {
        $currentTime = time();
 
        $currentYear = (int)date('Y', $currentTime);
        $currentMonth = (int)date('m', $currentTime);
        $currentDay = (int)date('d', $currentTime);
 
        $targetMonth = 4;
        $targetDay = 12;
 
        if ($currentMonth > $targetMonth || ($currentMonth === $targetMonth && $currentDay >= $targetDay))
        {
            $targetYear = $currentYear + 1;
        }
        else
        {
            $targetYear = $currentYear;
        }
 
        $time = '10:00:00';
 
        return strtotime("$targetYear-$targetMonth-$targetDay $time") * 1000;
    }
}