Our group met on Sunday at 3:00 in the Promanade Lounge. Here is a great tip: setup a Yahoo group account & have people join that group that are on your cruise. You can post questions, share photos, all sorts of things. Ours worked out really well.
Oh forgot to say why we met on Sunday. The first day is pretty hectic with getting on board, getting reservations, etc. so we figured Sunday would be easier for everyone.