Feeding pumped milk- how much?

Jessica

I want to start feeding my 5 week old a bottle of pumped milk a few times a week so that he starts getting used to a bottle in case it’s ever needed. Problem is that I don’t know how much to feed him. With breast feeding, he pulls off the boob when he is full. Will he do the same thing with a bottle or do I need to give him a certain number of ounces so he doesn’t over feed?