Well, we have had a minor miracle with the early bedtimes. Started Saturday, dd was asleep by 7.15, ds2 by 7.45, although there was a lot of crying involved and they woke four times through the night, awake at 5.15. Sunday, both asleep by 7.30, ds2 woke once, dd not at all, and awake at 5.15. Tonight was harder - we don't get home from nursery till 6pm, but still made it upstairs for teeth by 6.30, sleep at 7.40, lots of crying again though.
So, this early to sleep may work, if we can work out how to fit it in. That short evening meant they and I didn't get much time with ds2, and we skipped a family tea, so it can't be sustained in the long run, but I'm hoping a week or two might reset their sleeping hours, and we can start moving bedtime a little later and either keep the same sleep time, or even, dare I dream it, move waking towards 6am?
narmada thanks for the idea. I have never had the courage to try wake to sleep either. I do know if one wakes the other after 4am they can both be up for the day though, so I'm not convinced it would work for my pair.