Room Sharing

I was just looking for some advice on room sharing. I have a 3 year old, an almost 1 year old, and am due the end of December. We only have 3 bedrooms upstairs so I plan to have my older boys share a room.

I am just wondering when I should transition them to sharing a room? I know baby won’t be sleeping there until a few months after she is born, but I still want her to have her own room for diaper changes and night time nursing. I was thinking of getting the boys to share starting in November so they can get used to it before baby comes, but I don’t know if that’s just too early?

Anyone on here have experience with this?