I would choose one of the kids to be the "teacher" for calendar. The would get to direct the routine, pick which songs to play for fun and whatever else went along with calendar.
My kids knew that they wouldn't be picked if they were rolling on the floor... so it cut down behavior problems too.
I also bumped up the content of the routine so they wouldn't get bored. I added some "First Grade" type skills. Ask the First Grade teachers at your school what they'd like you to add.
