Every year I have my students glue this on the inside back cover of their interactive notebooks. It's the best routine I've found to keep my middle school students on a restroom pass routine and keeping track of the tardy policy on my campus.
As always teaching the routine of using this log is going to take teaching both your students and yourself to use this consistently. My students get 4 passes every 6 weeks (we are on a 90-minute block schedule). Once I've dated and initialed all 4 areas, no more passes, it's that simple. Students who have passes left over at the end of the 6 weeks get extra Dojo points before we do our class prize drawing.
The tardy policy on my campus allows students 3 tardy's per 6 weeks. This log has helps me keep track of that policy, helps my students keep track of where they are with their tardy's and it serves as great documentation for parent conferences when students are in truancy trouble.
When a student has permission to go to use a restroom pass all they have to do is get initials from me prior to leaving the room. Since the policy in my room is that students can only go during work time, I never get asked to initial anything in the middle of a lesson.
In regards to the tardy procedure, when a student enters late they get their interactive journal (which is already a daily routine) and drop it off on my desk until I've had a chance to initial and return it to them. Easy peasy!
Hope this helps!