The first core principle of effective training is – Expectations for the training must be known.
The trainees need to know, not only at the beginning of the training but also in advance of the training. At a minimum you should tell them:
• When the training will be held
• Where the training will be held
• What materials to bring to the training
• What subject(s) will be covered in the training
• How long the training will take, both duration and sessions
• Will they be tested on the training
• How the information will be covered
• The objective of the training session
• The anticipated skill or knowledge to be achieved

If you make your expectations and your intent known in advance of the training, there is more buy-in or at the very least there will be less time spent stressing out by the trainees when they are surprised by something in the training.

By doing so, your audience should be in their most receptive mode or stance. They will learn more, they will learn it deeper and retain it for a longer period of time.