Question: Introducing bottle to breastfed baby

Hi. I’m exclusively breastfeeding my 4 week old daughter. I was advised to try to introduce a bottle of expressed milk from 4 weeks, so that she’s young enough to take it without being fussy, but to not give her too much that she gets nipple confusion. My question is- how often do I feed her from the bottle so that she gets used to it, but not confused. I plan to breastfeed her until 9 months, so in theory I could skip the bottle altogether, but I would like it as a backup so I can go out alone.