Being on time is a coordination problem as well as an individual habit. Make the expected arrival, preparation and backup route explicit.
Define what on time means
A meeting that starts at 09:00 can require different preparation for a presenter and an attendee. State whether people should be ready to work at 09:00 or merely join then. Include the time needed to open a file or check equipment. When schedules span locations or time zones, show the zone in the invitation. Ask whether the meeting needs a fixed start at all.
Build a realistic buffer
Look at the actual journey or preceding task instead of adding an arbitrary five minutes. A person who must close a service desk at 08:55 cannot reliably appear in a different room at 09:00. Move one commitment, provide coverage, or allow a remote join. Transport disruption, disability and caring duties can require different arrangements; assess the work need rather than assuming one routine suits everyone.
Make missed starts recoverable
Publish a short agenda and decision log so a late arrival does not force everyone to repeat the beginning. Agree how someone signals a delay and who can start without them. Review repeated delays for a pattern in the schedule, meeting design or support. Focus feedback on the impact and a workable next arrangement, not a character judgment.
Try it in a real workweek
A weekly review starts after a shift handoff. The team moves it 15 minutes later, shares the agenda in advance and records decisions. It checks whether meetings now start promptly and whether shift coverage remains safe.
A punctuality policy should not hide an impossible rota or punish people for access barriers.
Check the source and the context
For the next step, see this related field guide.