Notifications should go off on the
days that are due for your habit at the time you've set in your
habit settings (the app's default is 6pm). Please note that a
notification will not fire if you've already checked in for the
current day earlier than the notification time.
Also, please ensure that the app is allowed by iOS to send
notifications. You can do that by opening your iPhone's settings
-> Notifications and verify that the respective settings for
Today are enabled.