Hmmm. I'm afraid I'm not going to be very helpful, but at our house it has been an extremely slow, gradual evolution. I have a nearly 7 and a nearly 10 year old who both still sleep with us to some extent. When dd1 was 6, we bought bunk beds for their "room" and she wanted to sleep in there. I began reading to them while they were in their bunks and my 6 year old had no problem falling to sleep while I read. My then 3 year old sometimes fell asleep, sometimes I took her to bed with me. It was her choice. Now, at nearly 7 and 10 with a bedtime routine we stick to most nights, they go to bed in their room without any problem, but often migrate in the middle of the night. Dd1 does this a couple nights a week and dd2 most nights.
So, I think it was the novelty of new beds that really got dd's interested in sleeping in their own room, and it was important that they knew they were welcome in our bed anytime they wanted to join us.
I still love waking up with them in bed with us. I'll be sad when their nightly migrations stop completely. Cosleeping has been wonderful for us, it was something my that my dh wasn't sure about in the beginning but has also come to love.
So, I think it was the novelty of new beds that really got dd's interested in sleeping in their own room, and it was important that they knew they were welcome in our bed anytime they wanted to join us.
I still love waking up with them in bed with us. I'll be sad when their nightly migrations stop completely. Cosleeping has been wonderful for us, it was something my that my dh wasn't sure about in the beginning but has also come to love.