The good news is, that long awaiting functionality appeared in the GTD Simple. Since version 0.5.1 GTD Simple reminders are working. You can schedule reminders associated with scheduled tasks. Reminder can be triggered in the same time as the task date, or you can define date and time it will be triggered.
You can install the GTD Simple app from Google Play:
How does it work? Quite simple. When you have some tasks that should be done at particular time, you shuld set a due date. It makes GTD Simple put it into the Scheduled Tasks directory, and additionally – it will add an event to the associeted calendar (if you have associated one).
Now you will see this task every time you will check the calendar, or Scheduled Tasks. But if you dont check your calendar every day, it is better to make GTD Simple to notify you, that there is something to do. So you will be notified if tou set a reminder in such task.
While setting the reminder you have few predefined values: on time, 5 minutes before, a quarter before, one hour before, a day before, a week before. But if none of those predefined values fits to your needs, you can set the date and time manually.
I hope you will find GTD Simple useful!