Keep a todo list with due times and notifications.
Limit Notifications need notify-send.
2 open-source tools on osfeed do this, in 2 ways. Each entry says how, and where it falls short. Read the tool's page before you rely on it.
Limit Notifications need notify-send.
Get notified when a tool adds, fixes or changes a way to todo list, including tools added to osfeed later.