I also need this feature. From the forum:
"I want to create rules to once the ticket is received at a specific time let say over night it be assigned to a different group or user. Also the same for over the weekends use different user, etc. I have seen around the rules, but can not find any time rule that works for me.
Does GLPI supports this? if not I would be interested about helping developing such a thing. Any work planned or any help with be welcomed."
GLPI forum topic.
Customer support service by UserEcho