Ok, first of all, I'm looking for something specific like a scheduler or something.
My problem: I want to run a specific function (lets call it doSomething()) exactly once a day, at night (like 03:00 am).
I was looking for something like this, and I found the function "wp schedule event". However, in the documentation, it says "The action will trigger when someone visits your WordPress site, if the scheduled time has passed."
This is not what I want, the function should be called when the scheduled time has passed, regardless of whether or not a visitor visits the website.
(That's the main reason why I want to run this once at night, cause it will pull data from many locations and put about 70 000 records in my database, I cannot let a visitor wait 2 minutes to load the website, just cause the function is running...)
Is this possible in WordPress?