Lose the day sleeps. Worked wonders here.
They get very grumpy by 4 to begin with but after a week or so they are falling asleep on their feet by 7:30 (mostly lol)
Also try turning tv etc off for at least. 30 mins before bedtime even if they aren't directly watching it. Curb what ever you are feeding at dinner ie cordials or other stimulants, fruits, etc.
[sorry so brief on my phone]