So we were finally ready to put Owen in his toddler bed in his new room. Ben installed our new video monitor and we felt prepared for whatever would go down.
We did bathtime as usual, then headed into his new room for jammies and a few books. Then it was lights out. He has a nightlight and we put a babyproof thingy on the doorknob so that he couldn't open the door. (Yes, I feel a bit like we were locking him up, but it is for his own safety since we don't have a gate at the top of the stairs.)
Ben and I immediately turned on the monitor and watched. He laid in bed for a few minutes, then was up and walked over to the door. He just stood there and looked at the door for a few minutes, then decided to go lay back down. Ten minutes later he was back over at the door, then back in bed. He repeated this about 5 times. Then I realized that I had forgotten our nightly tradition of singing "Twinkle, Twinkle" and I thought that might help him to recognize that it was bedtime. So I went in, sang to him, then said goodnight and closed the door.
That did it. He was such a good boy and slept through the entire night until 7:30 the next morning. Easier than we had thought it would be.