Room sharing

Er

I found out I'm pregnant with baby number 2! My son will be four when baby arrives and they will be sharing a room once the baby is 6 months. How did you start getting your toddler ready for room sharing? I was considering, once I'm far enough along to get a crib and put it in his room with a baby doll in the crib to sort of get him use to it? Any tips? Tricks?

Thanks mommas. We live in a two bedroom town home that we just bought a year ago so we are trying to figure out the best option.