Indy 9 in a Cyber Cafe software

I am developing a LAN House software with Indy 9.
After the user logs in the client machine, at every second the database and
both the server and the client GUI  will be updated with the remainning
time,
time elapsed and the session ending time.
What is the best aproch to this?
A timer on the client, sending the information to the server at every
second?
A timer in the server, sending the information to every connected clieint?
A timer for every client on the server?
Other suggestions?