Maybe this is not so difficult. Can a service worker, after it has started, set some sort of public variable indicating to the main of the project, that the reload has been completed and it is aok to now load the first real page. Also, the initial startup from cache would hold waiting for this flag until the refresh killed it. Then on the reload, the main would again wait, but will, once the reload completes, get the signal to start.
This assumes firstFrom is pointing to a splash screen that you don’t care if it’s the old version or the new, we’re more concerned about a flaky looking UI.
Taking this further, can the service worker set a flag that it is refreshing the components? Maybe we could slip in an additional “splash screen” stating “downloading new awesome”.
EDIT
See this post for additional information. Modifying PWA.js code - #7 by GaryGorsline