Our DD (3) has been starting the night in her own bed since last year Feb but she doesn't sleep through the night in her own room. When she sleeps in my bed, she sleeps through the night most of the time. DH works night shifts 5 times a week so on those nights I usually carry DD into my bed when I get into bed so we can both sleep all night.
I'm due in 2 weeks with #2 and we're trying to figure out sleeping arrangements. I've heard it's not safe to have a toddler next to the newborn, which makes sense because DD often tries to get as close to me as physically possible so I could see her rolling onto the baby.
So I figure I'll put the baby on one side and DD on the other, but then I'll only be able to nurse from one side laying down and I'll get engorged. I guess I could sit up and nurse the other side then put the baby back down but being able to stay laying down while nursing is one of the biggest benefits of cosleeping.