18 month old and a 4:30 wake up

[2littlegirls mom]

My 18 month old has been having early wakings for quite a while  (perhaps more than 5 months).  She would wake around 5:30 and then move towards 7 and then back again.  It would fluctuate.  But in the last few weeks she is consistently waking around 5 and pushing towards 4:30.  I can go in and shush her.  She lasts another ten minutes.  I don't feel I can pursue a noisy attempt back to sleep since her 3 1/2 sister sleeps in the same room.  Her schedule:

Wake:  4:30-5
Snuggle on couch with me until 7.  Usually she plays during this time, but the last couple days she's actually napped on me until 7.  The 7am waking prohibits a 12:30 nap.
Breakfast: 7
Lunch 11:15
Nap: 12:15/12:30 (but none when she wakes at 7) for about 1 1/2 hours
Snack: 3
Supper: 5:30
Bedtime: 7:15/7:30 (asleep immediately)

So how do I fix this early waking?  Do I push the nap later and thus the bedtime?  How do I make the bedtime later when her older sister needs to be in bed by 7:30 (sleeps until 7:30 when I wake her)?  Recently she has been having 1-2 night wakings (around 10-11) except for the last two nights, which followed two napless days.

Did I mention I'm tired? 

[brightside]

Not sure how you can get round it but I think if you go to her and let her sleep with you then she is going to become dependent on that and less likely to put herself back to sleep. And she obviously needs to sleep or she wouldn't sleep on you. I can understand the difficulty with having another child in the room though.  Also, I don't understand about the nap-are you saying that if she sleeps until 7, she won't nap at dinnertime? That seems a little strange as most children at that age would definitely need a nap in the day, even if they got up at 7. Perhaps you are trying the nap too early or too late and that is why she won't go to sleep? At 18 months, we had some sleep issues until we did WI/WO and i do feel that there is a developmental blip around that age but I also came to the conclusion that when DS woke early it was often because he had gone to bed too late and had become OT.

A typical day for this age would be something like;
wake 7am
nap 12-2
bed 7pm
Although, we have yet to actually have a typical day! 

[2littlegirls mom]

Well, it seems she took a nap today closer to 3 when she fell asleep in the stroller.  She was tired.  It just seems that a 5 hour wake time is not enough when she's used to being awake 6-7 hours.  Other than that 5am waking, she is quite close to the recommended routine.  She doesn't usually show signs of tiredness other than sleepiness at lunchtime and the recent accumulation of a sleep deficit.

Did DS have a lot of crying with wi/wo?  I'm certain DD #1 would wake (as she did Sunday) and then I'd have trouble on my hands.

[brightside]

Yes, there was a lot of crying the first couple of times I did it but he quickly learnt that I wasn't going to give in and then it became more of a whinge than a cry. Only took a couple of days.