How long should animation delay be for a user interaction?

Simple question from a dev... I'm a non UX expert. When does a action, such as press a button or hover over a icon, how long should I delay the animation to show the interaction?

I looked on Google Design and for their drawer/side panel button I saw the animation delay was 0s.

EDIT: I believe there might be a misunderstanding in which I apologize. I am asking how long show the delay be before a animation starts, not how long a animation should be.