There are so many methods of starting the first class. The aims are many: to relax the students, to provide introductions, to explain the course, etc.
I find that it really depends on the student population. For example, more experienced and older students (e.g. adults) usually like to cut to the chase and trim out all of the unnecessary introduction material. Younger and less experienced students usually need more time to adjust to the new environment, and they require more assurance.