Notify user of approaching date

[Carlos_Alberto_Leonel]

Guys, I need help. I’m creating an appointment scheduling system and I need to notify the user:

• When it is within the deadline;
  *When the deadline has passed;
  *When there are x days left before your appointment.
  Give the option of how many days he wants to be notified of his appointment.
  In the User Notification videos there was a native component (Experimental): “Notification”. In this current version there is none. Is there any other or any extension that can be used?

Example:
Consultation date: 03/27/2024
Number of days I want to be notified: 2 days in advance;
Notice date: 03/25/2024

I created these blocks experimentally:

[Carlos_Alberto_Leonel]

Guys, I haven’t tested it yet but I thought about using this procedure here.

[Taifun]

how often do you plan to open your app to check, if you have an appointment?
usually you use the alarmmanger to send a notification at the given time

App Inventor Extensions: Alarm Manager | Pura Vida Apps

Taifun

[Carlos_Alberto_Leonel]

Thanks .
But is there any other alternative that is free?
If I don’t have it, I’ll buy it.