Note this assumes we are talking about PM and has a leading 0 so 8:00 am would be 0800.
<?php
$HourMin = date("Hi");
if(($HourMin > '2000') && ($HourMin < '2050')) {
echo "display the 8:00 image";
} elseif ($HourMin > '2050') {
echo "display the 8:50 image";
}
?>
Hope that helps,
Richard