After the ship sails a bit we can find out activities by word of mouth.  I agree it is hard to plan specifics.  But, we know things like Match your Mate are a given on pretty much every cruise.  Trivia is always going to be a staple.  Some sort of craft will be offered, Karaoke, etc.
You won't be able to figure out to the hour or minute what will happen until you are onboard.
MJ