I see that olivier158 has been asked,

to do a workshop

... and needs to know,

How much time to do that ? 1h ? 3 h ? 5 h ? something between ?
Is there a planning, a way to do that ?

A written handout is important to provide.  You can have concrete examples, diagrams of setup, lighting, composition rules, ... and a bibliography as well as a list of suppliers. 

If you can get yourself to create the written handout well in advance of the presentation, by reading the presentation, you will know how long it will take to give ... plus allowing time for questions.  

--
Martin