I completely get the idea that 6am is too early! I feel the same - luckily my DH gets up with my DD at 6am and lets me sleep. I think the idea of just letting your LO play in her cot for a little while if she is happy to do so. That way you can doze (or get up and have a coffee!).An 11 hour stretch overnight is fantastic at 6 months old, so I would be hesitant to change anything just to try to get her to sleep later.