Set a custom start time for the "daily" interval when using Limit Orders for WooCommerce.

limit-orders-custom-daily-interval.php

<?php
/**
 * Plugin Name: Limit Orders for WooCommerce - Custom Daily Interval
 * Description: Restart daily order limiting at a time other than midnight.
 * Author:      Nexcess
 * Author URI:  https://nexcess.net
 */

/**
 * Get a DateTime object representing the start of the daily interval.
 *
 * @param \DateTime $start    The DateTime representing the start of the current interval.
 * @param string    $interval The type of interval being calculated.
 *
 * @return \DateTime A DateTime object representing the starting point of the daily interval.
 */
add_filter( 'limit_orders_interval_start', function ( $start, $interval ) {
	if ( 'daily' !== $interval ) {
		return $start;
	}

	/*
	 * Set the time the interval should begin.
	 *
	 * - $hours should be 0-23 and will be based on the store's timezone.
	 * - $minutes should be 0-59.
	 * - $seconds should be 0-59.
	 */
	$hours   = 20;
	$minutes = 0;
	$seconds = 0;

	// If the given time occurs after right now, adjust it by -24 hours.
	$now  = current_datetime();
	$then = $now->setTime( $hours, $minutes, $seconds );

	if ( $then > $now ) {
		$hours -= 24;
	}

	// Set the interval start time.
	return $start->setTime( $hours, $minutes, $seconds );
}, 10, 2 );