Room sharing?

Mika • Baby #1 - 06/14/2019 Baby#2 - 10/06/2020

Does anyone have any experience and/or tips for room sharing at a young age? My daughter will be 18 months when we’d likely move our 3 month old in her room. She sleeps through the night like a champ so I really don’t want to ruin that 😅 HELP!