You've given it thought - let your students do so, too. Written language gives clear signals of meaning. Spoken language has different and more subtle signals. Pay attention to them. Think about your delivery.
Variety is the spice of life - so, too, in classroom delivery.
What works for three minutes may not work for seven. Switch deliveries - as in baseball, it's the pitch itself as the change of pace. You're ready when class begins because this is your life and your discipline. That's not necessarily true of your students who are coming into the room from many different places with many different concerns. Ask a question or two.