How long do they sleep for? I've always thought that "sleeping through the night" for a newborn is 5 hours unbroken sleep, so if they go down at 7pm, that means them being awake again at midnight. And then what happens if/when they do wake up?
I'm asking out of genuine curiosity as my DD (who is now a strapping toddler) would never go to sleep that early in the evening. She would cluster feed during the evening and would eventually go to sleep at about 11.30-midnight. Even when she was a bit older (6 months or so), any sleep she had before about 9pm would turn out to be a 40 minute nap, then she'd wake up and be awake for another couple of hours. It has taken a long time and a lot of patience to get her to go to sleep (and stay asleep) in the early evening.
I guess this is where the phrase every baby is different comes in, but I do remember feeling a bit in awe of my friends whose babies went to sleep at 7pm and stayed asleep.