While new products will be added to the FOS datastreams by the NWS, it will not happen immediately. That means that the average rates expressed below should be a good indication of reality for at least the short term. Time synchronization facilitates generating statistics and tracking products through the IDD fanout. Each product sent in a datastream is time stamped when it enters the system. If a node in the system is not synchronized with the other nodes, it could appear that a product arrived before it was sent or that a product was delayed longer than it actually was.
Documentation is available with the distribution.
Once you have xntp installed, you need to negotiate with server sites. Your site should have at least three time servers. If you have a central computing facility on your campus, they probably have an NTP server running and can act as one of your servers. They can also help you to connect to two other servers. The documentation that comes with the xntp package will give you further instructions.