Last year was supposed to be the opening day of rivers of light. Obviously that got pushed back.
For the past few years jiminy cricket has met at rafikis planet watch. His line was usually around an hour so if you want to meet him (this is the only time of year he regularly meets anymore) go early when he first starts for the day.
Last year Joe Rohde was on hand to sign one of his animal prints. There was a limited number of wrist bands and you could get one upon entry to the park. You had to pay for the print but all the proceeds went to Disney's conservation fund, which I like to support.
Keep your eye on the Disney parks blog, they'll most likely announce activities closer to the day.