I divide the number of students by the number of days that I need to spend on this activity. I model how to proofread papers on the overhead using my paper or another fictional student's work. Only the first group of students would take out their papers on the first day. I would sit at a desk alone. Students would be instructed to only mark corrections to student writing if both partners agreed that a correction was needed.
Corrections are to be made in pencil.
I am the only one who can make a correction in pen. I also pass the sample on. When each paper gets back to the original starting points, the class is over. Papers are returned to their owners. This repeats until all papers have been proofed.