Hi,
I have just had my third baby. And my two eldest 8 and 6 are still in bed by 6-6.30pm. They have always gone to bed at this time and sometimes since bubba has arrived it has been later, but now 3 months in they are all in bed and asleep by 6.30pm. I start the night time routine as soon as they get home from school. We eat really early, anywhere between 4.30 and 5.30 depending on the weather and how organized I am with food. Our homoeopath told us that the best time for children absorb nutrients from food is between 3 and 5pm, so instead of afternoon snacks we try and have an early dinner, and then a snack before bed if they need.
Our night time wind down since they have been tiny is dinner, bath, book then bed. After dinner, it's quiet time, no more playing and loud talking very quiet, its winds them down ready for bed. I LOVE having the house so quiet so early, it started when I was a sole parent and it has continued into our new family life... works for us, not sure it works for everybody. they are up between 6-7am but happily play until I get up, if it's weekends they wait a bit longer then through the week. I get up to do lunches etc at about 6.30.