Check if its thursday after 3PM, saturday or sunday or monday before 9AM.
if((date('N') == 4 && date('G') >= 15) || in_array(date('N'), array(6,7)) || (date('N') == 1 && date('G') < 9))
date('N') gives you the weekday (From 1 for monday to 7 for sunday), and date('G') Gives you the hour of the day.