Syllabusters Are Outdated — from scholarlyteacher.com by Todd Zakrajsek

What does this all mean for the first day of class? Approach that first day with “learning-centered” in your mind. Focus on learning. Learning is all about curiosity and desire. Desire to know, to figure things out, to be surprised, all getting that dopamine flowing throughout the brain: That is what learning-centered is all about. An exam is best thought of as feedback, showing whether students are learning, not a date to cover on the first day and dread every class period in the meantime. An exam should never be the reason to learn, it should always be an indication of learning. Don’t spend your first 45 or 85 minutes focused solely on exams, term paper deadlines, and attendance policies. That moves teaching toward an artificial transactional arrangement where students learn in exchange for points and grades.

From DSC:
I would highly recommend starting out with a major HOOK. Some question, some video, some recording/piece of audio, etc. that would provoke interest, curiosity, or even some emotion. On that first day, the following item MUST be addressed if you expect to engage your students:

Why is this class/topic relevant?

Start with that. Immediately. The other stuff can be introduced later on, as Todd mentions.