I thought it woul make them wake up earlier too, but that hasn't been true for us. If they've not had enough sleep, and I put them to bed earlier, they sleep later. My 3.5 had a messed-up week last week and was up late. This week, she's been going to bed between 7-8 and sleeping until 8-9 a.m. Yep. 13 hours sttn. It's glorious.
Well, it'd be more glorious if her younger sister did the same thing.