Since my two were 2 and 3, when I went to bed, I used to put a tupperware box with some biscuits and a drink in their room, so they could have a snack and play. They were not to come and wake us or come into our room until they heard one of us go to the bathroom, (heaven help you if you needed a pee at 6.00am!!)
I didn't buy one of those bunny clocks as I think they are a bit naff, all tacky plastic, but a few friends swear by them. I just put coloured tape on a large face alarm clock, of their choosing, they knew that they were n't to get up until then. They were able to get up and go to the loo themselves if need be.
Mind you, I found keeping them up later never worked as they were then overtired. They were always in bed by 6.30 and light out at 7, by 8,9,years old, bedtime was 7.30 for 8 o 'clock light out. I can't believe that people let their kids stay up so late these days. I don't think children get enough sleep, and as someone who has spent a lot of time in nursery schools, reception classes, we all knew which children hadn't had enough sleep as they were desperate by 10.00am.
I don't believe in a strict routine, but bedtime was one thing I was firm about, I never had broken nights, thank god!
Now ours go to bed after us and don't get up in the morning, as they are teenagers, so you can't win!