5yo waking at 0430 since staring school

[Rathkelter]

Has anyone had this?
We went through the 0500 waking when they were babies which improved but had never quite managed the 0700 holy grail start. Now DD, since starting school, has been waking to start the day at silly o'clock. Goes to bed 7-8pm. I can't get her down earlier due to work / logistics. I need to work at night and hit the sack around midnight so am rapidly ageing due to sleep deprivation.... advice greatly received.

Have you tried rapid return / gro clock to explain that nothing will happen until 7am? So no talking just 'back to bed darling, it's nighttime' then repeat repeat repeat. Likely to kick off the first few mornings but should realise if you are consistent, that might as well just go back to sleep...

Just tell her to stay quietly in her room until 7 or whenever?

She is 5. My now 3 and 4yos have been doing that for over a year now.

GroClock used to always work. We were strict about it and had no issues; she waited until the light came on. But now, if she wakes at 0430 and can't get back to sleep, it's a long wait. She lies there for a bit, then starts whimpering and if her volume escalates I worry she'll wake up her older brother. Tried sticker charts, the lot.
I thought we were out of the 'early waking' woods but this is phase 2!