<?php
$time = time();
$start = strtotime("now 00:00:00";
$from = $start+54000;
$to = $start+54600;

if($from<$time && $time<$to)
echo 'Сейчас '.date("H:i",$time);
Добавлено 16.03.16 в 19:46:27:
как вариант