The timer is on leaving group, not joining them. It's a penalty for not being loyal.

even when you join your first group you get the timer and group was dead no leader or senior , and no way replace them, so no one to sign group up for event and no one give out extra reward to last event that was sign up for, why to many bad thing done to you ,when you leave group even when do not leave on your own.. Lose all your training point did not use yet, can not join another group for 8 hour even when you do join another group can not do anything with new group for a week, can not get group activity reward for a week. it enough make people stop playing and take their time and money some where else... And could be very reason people stop playing...