Table in https://community.windy.com/topic/3340/when-and-how-often-are-the-weather-data-updated has some errors. E.g. GFS 0.25° Runtime (aka. Reference Time on Windy UI) is not 00:15, 06:15, 12:15, 18:15, it is 00:00, 06:00, 12:00, 18:00 UTC instead. Grib files of GFS 0.25° model are disseminated on NOAA site only about 3h35m after each runtime.
About availability of models on Windy, the best choice is to click the "i" control just above the model selection bar: it provides Last Update Time as well as Next Update Time on Windy server side for currently selected model.
