The date given on a received weather forecast in Navstation is the Analysis time (start of forecast), and an updated forecast will be available about 16-22 hours later if you have a scheduled forecast every 6 hours. Meaning the date/time for the START of the forecast corrected with all available observations from surface and satellite; this is normally very close to the observed WX world-wide.
Then the numerical models will run for a long time to make a 15 days global forecast. This process, including transmission time of very large files, takes approximately 15 hours to be uploaded to NAVTOR server, and additional about one hour to reach all vessels world-wide subscribing to NAVTOR Weather service.