Remind user to catch up

[IMP1]

Keep track of the last time that the app was opened. And if it was a while ago, then ask if you're all caught up, or suggest someone to catch up with, or something, as a push notification.

[IMP1]

Notifications after a week, a month, and then maybe every month?

Options to Ignore, Set Reminder, or Remove from the catch-up group.