Trigger on date

I am looking for a specific way to trigger a notification. I have a website where users can make there goals. On these goals I want to attach triggers with reminders, so users are reminded to keep focused on their goals.

Something like:
1. I want to be reminded every day at 8 o clock.
2. I want to be reminded on a specific date at a specific time
3. I want to be reminded …..

So this is the trigger I was looking for. Hope you can help.

Thanks!