On the Western Itinerary you pick up your free passes on Monday (sea day) at 9:30 am in front of Studio Sea, Deck 4. Get there early because a line forms at least 20 minutes ahead of time. There are two sessions of Tea with Wendy to choose from.
You can pick one session either that day or on Thursday, the other sea day. First come, first serve and the passes do run out. I believe the actual Tea is at about 2:00 pm in Studio Sea (Wendy will pick either two little boys or two little girls (preferably boys because they are supposed represent her two younger brothers). Photos are allowed and the whole tea lasts about 20 minutes or so...not very long.
Not sure the schedule on the Eastern Itinerary. I got this info from personal experience and from just checking my Navigator from the 1/4 cruise. Oh...parents are welcome so the number of passes handed out depends on how many family members attend. As I said, passes go quickly so if the whole family is not really sure they want to attend, don't take a pass for everyone because it will leave some people who really want to attend with none.
MJ