Here is the reason not to send materials to people in advance of a presentation: "If I send them all of my content, they won't need me, they won't be impressed by me, they will be ready to poke holes in my data, and they will have ammunition to use against me. Better to keep them in the dark!!!"
That's the reason I use here, but it's just not a good reason.
I want you to give a pretty good presentation—really, I do. And I want you to be lazy. The more content you give your audience in advance, the more they will be familiar with your ideas, and the easier it will be for them to grasp what you're saying during your speech. All of this works to your advantage.
Now, you might be thinking, "But my group is too lazy; they will never read any of the advance materials!" Well, that's all the better. Now your audience has seen you send stuff, and they feel guilty for not reading it. You get credit for being thorough, and they are on the defensive; either way, you win.
I think you should send out as much info as possible the moment you have a booking on the calendar for your presentation—even if it's months away. Then send something out again a few days before—even if it's the same content.
The final fear people have is that audiences will complain if the same material is covered in the speech that is covered in the text. Relax; this will not happen. As long as you don't ...