I took a page out of my own book today

I'm always giving people my unsolicited advice about babys and bedtime. It worked wonders with L and it worked really well when Z was a much younger baby. But for some reason I've been terrified of trying it with Z now that she's a little older. I swear by this method, so why am I so hesitant to try it? What the hell is she babbling about you're probably wondering? Well I always put L to bed very early and she's always slept until at least 7 am even as a baby. I have found that the later she stays up the earlier she will wake up. When L was under a year old I started putting her to bed at 6 and she'd sleep until 7 the next morning. I did this with her until she was around 3 and then I started keeping her up until 7:30'ish.
Well Z wakes up most mornings around 5:30 and she's miserable. Tonight I put her to bed at 6:15(she usually doesn't get to bed until between 7:30/8:30 depending on the chaos around here). She fell right asleep. Will she prove my theory correct and sleep until 6 or is she going to wake up screaming bloody murder and demanding breakfast at 3 am? I'll let you know tomorrow. I'm praying to any and all powers higher than me to keep her asleep until at least the sun rises. PLEASE!!!!!!!!!!!!!!!!!