If you are referring to a ZVV day pass, it is only valid after 09:28. It is therefore valid until 09:27 the next day.
A ZVV 9-o clock day pass could be an alternative, it is valid from 09:00 to 05:00 AM the next day, on weekends even from 00:00 to 05:00 AM, and a bit less costly than a 24-hrs day pass. It all depends on your needs.
If you get on a service before the ticket validity you risk a penalty of CHF 100.