How can I send users notification as a reminder before a time in the Firestore document?
For example an event is taking place 1. of December. The document was created in October, therefore I can't directly trigger a push notification from the app. Now a week before the event I want to send a push notification to all the users registered in that event to remind them about it takin place.
I suppose it has to be done with Cloud Function, but I don't know how. Could anyone help me, please?