When are Interruptions signaled and launched?

Hi,

(I know how IE/IF sets the trigger, so that's not the question)

So i find this a little bit confusing.

From my understanding, the Interruptions is launched before fetching the next instruction.
But is that also when the check for IF/IE happens, or does that happen on the cycle where either IF or IE is changed?

Cause you could basically set/unset IF/IE within one instruction cycle, and then when fetching the next instruction,
it would look like nothing happened etc.

Thanks:)