Whatever you call it, a Do Now or Jumpstart has become a widely used method to start class. When I first started using one, I wasted a significant amount of paper trying to figure out a method that would work for my students and me.
Eventually in order to increase the participation and value of our Do Now and to conserve paper, my classroom switched to a Weekly Do Now sheet. Students pick this up on their way into class on the first day of the week and then keep the same one until I give it a grade on Friday.
I have found these to be incredible ways to hold students accountable for weekly work and if you are ever in a case conference or parent-teacher conference, these Do Nows are very useful. "Notice Mrs. So-and-so that your son was either absent or non-compliant on two days each week." That should help to explain why little so-and-so has a bad grade.