Currently, in the calendar view, if your period is "late", there's a dialog asking if this period has started yet, with three choices: Yes, Not Yet, and Edit.
If you select "Not Yet", nothing happens. The predicted period is still in there until you log a real one, and the tile assumes that it's correct. [Commonly, this can be a number of days or even weeks.]
If you select "Edit", you can't log a period in the future or postpone the prediction (and it makes a joke about having a proactive attitude). For now, until the "Not Yet" button is connected to a function on the back end, it should be removed.
This is relevant because for most menstruators, cycle length is not constant, and "lateness" is normal.
Moderator Edit: Clarified subject
... View more