How to define certain step in the app where user will be asked to sign up? If there are requirements, that the daily task manager app design should contain sign up & login. But what if we don't want user to sign up from the first interaction with an app. In such case we have to define on which step ask user to sign up. And I see that in many to-do apps such as "Any.do", "Wunderlist" there is sign up screen from the beginning in a way to sync data throughout all devices straightaway.
Following other strategy I want to give user an opportunity to use the app as simple grocery list without signing him up yet. Only when user will want to make a note inside subtask/split and manage small tasks/use file-drop capabilities/share task with someone else (extend grocery list app to a GTD let's say) I will ask him to sign up. Is it correct way? For people who want to backup tasks to the server from the beginning, I will include this option somewhere in settings of the app, so it would be available, but optional first.