I also just finished sending out an email that gives my travelers links to the Remind "class" that I set up for large scale communication and the private Facebook group I created so that we can share pictures and updates more easily. Meanwhile, every traveler will need to download WhatsApp and connect with their chaperone's group once we get to the airport. I want to use WhatsApp only for the travelers so as not to disturb (or worry) anyone back home.
I've already discovered things that I would like to do better next time, but I'm thus far rather happy with the process. It's taken more time than I anticipated (even though my rule of thumb is that most things take longer than one expects), but I don't feel that much of that time has been wasted. More importantly, I believe that we are going to have a fantastic experience which will make all of this time well spent.