How long until Construct 2 detects a new game version? The description of offline games and the browser object doesn't really explain how long it takes for Construct 2 to detect a new game version and to begin downloading it.
It's a cache problem maybe ? If you are running your game on a browser try to ctrl+F5 on the page, the cache will be deleted and you should see the new version.
....why are so many people giving irrelevant answers to my questions?
Because your questions are unclear ?
Well have fun with this "problem".
It's not a problem? It's a question?
Develop games in your browser. Powerful, performant & highly capable.
It should begin once the game has completed loading the current version automatically in the background. You can check the status of updates using the browser plugin (just set a text box to that value if you want to see it).
Construct 2 doesn't detect it, the browser does. For example open the browser console in Chrome (ctrl+shift+J) and you'll see status updates as it checks for an update and downloads one if it is found.