When do we move the chains and change the downs box, and on whose signal?

The rule book's recommended procedure is:

1. After each play the Referee signals the number of the next down and visually checks that the downs box shows it.
2. Each time the distance chain should be moved, the Referee signals for it to be moved, and checks that it is in the proper location before signalling "Time In" for the next play.
3. The Down Judge repeats the Referee's down signal, checks the downs box placement and number, and only on the Referee's signal directs the distance chain to be moved, then checks that it is stationed correctly.
4. Downs box official: change the location of the downs box and/or the number of the next down only on signal from the Referee and the Down Judge.
5. Yardstick officials: move the distance chain only on signal from the Referee and the Down Judge.

Source: Canadian Amateur Rule Book for Tackle Football 2026-2027, Case Book comment 3-4-1 (recommended procedure).