My 8 month old daughter (9 next Sunday) has been sleeping through the night when she around 2 months. However when she hit around 7 months, putting her bed has been harder but she will eventually fall asleep. Now the issue is she will wake up at least once every night, some times twice but will go back to sleep and sleep through the night from there. With that being said, it seems now she'd rather sleep with us in our bed even though she's been sleeping in her own bed since she was a new born. We co sleep in that her crib is next to ours. Some times we wait till she's in deep sleep to put her back in her crib, other times we'll let her sleep with us. I've noticed that when this happens (meaning when she sleeps with us) she'll tend to sleep through the night.