My advice on this is you look at how she's measuring. Our son was 90% on the weight/length chart and our doctor basically said "he's fine to sleep until he wakes himself up hungry" so around 3 months I had the night shift and rather than wake him up I let him sleep. I ended up waking him up around 6 hours then we did that for a week or two and then we just let him sleep as long as he wanted. He was good to sleep 8 hours a night from then on.
We didn't have a rigid set schedule, but we kept a routine. Before we'd lay him down we'd make sure he had his last bottle and a warm bath then fresh diaper. When we laid him in the crib though we didn't get him back out of the crib unless we were changing him or feeding him. He cried the first few weeks, but letting him "cry it out" was the thing to do. He's almost 9 now and still sleeps through the night without any issues.