interface - What is the minimum waiting time after when should a page loader be displayed to the user?

I haven't been able to find answer to my question from the internet, so maybe someone knows how to help me.

What is the minimum waiting time after when should a page loader be displayed to the user?

For example, I have a situation where the page loads quite quickly, but there is a rule that page loader should be displayed no matter what, so as the loading time is short, the loader only blinks/flashes.

Now I'd like to know what is the best practice for a rule "show the page loader only when loading time takes more than ... seconds".

Loader example:

Answer

If loading time is more than 1 second.

It is one of the classics, going back to 1968.

1.0 second is about the limit for the user's flow of thought to stay uninterrupted, even though the user will notice the delay. Normally, no special feedback is necessary during delays of more than 0.1 but less than 1.0 second, but the user does lose the feeling of operating directly on the data.

This one is from Nielsen but it is originally from Miller.

It seems that you don't know how long the page is going to load so the rule that you should show the loader no matter what is valid. But you could fade it in during the first second so if the page loads faster the blink/flash isn't that noticeable.

Or if you want only to show the loader after one second there still is a change for it to blink/flash really quick if loading is complete after 1.1 seconds. So you could only start to fade the loader in after one second.