Budgies aren't adjusting to sleep schedule

[...74]

So I've had my Budgies for around 7 months now and I've been trying to get them used to the sleep schedule of my cockatiel because they're in the same room and my cockatiel needs 15 hours of darkness but my Budgies have been waking up like a hour or two before they're supposed to and I'm worried they're gonna wake my cockatiel so I was wondering if anyone had any tips

 

[Emma&pico]

Hi
How do you manage sleep are budgies waking up in dark or do you cover cages let natural light in ?
maybe a black out blind in that room if you don’t already have one