Whitch function will called faster bound with delegate or set in SetTimer().

Hi I’m new to UE.
Suppose I have a function1 set in SetTimer().
On the other hand, I have a function2 bound with delegate which execute ClearTimer().

Here I have a question.
What time function1 called finally?
I don’t know when is function set in SetTimer() called in the tick.
Then calling ClearTimer() can cancel function1 call in the same tick or the cancellation held in next tick?
I mean once delegatge fires maybe function2 called next tick I guess.
Then function2 executed, function1 never called from next tick but called in this tick?
And I never want to call function1 after function2 called.
Should I check if function2 called in function1?

Thanks in advance.