Hey C.,
I have a 4mo old daughter and I agree w/ the advice given to you. Each baby will have their own sleep time, and it will usually change (mine did anyways) We TRIED to encourage our daughter to sleep around 6 weeks w/ the following: For us what worked well, was turning down the lights, TV, etc around 9ish. It would then take roughly an hour or so to get her into deep sleep, so usually she would sleep by around 10 or 10:30. This time worked well for me, because then she wouldn't get up till around 2 for a feeding, and then another one around 6ish, which by that time I was up anyway. That said, this "routine" was very flexible, as some nights she just wouldn't be tired until 11 or sometimes even 12, although we always did the lights off, noise off at the same time.
However,I do want to let you know that the actual sleep time varied greatly. At around 3 months, she decided, either out of comfort or hunger, that she would wake up 3-4x a night to nurse. So, even though we kept her bedtime the same, she is waking up more frequently. After talking to her Dr, and doing research, she is doing what most infants at this stage do. Apparently at this age, she is so intrigued by her world, that she is not eating as much during the day, and therefore compensating at night (I still try to feed her every 2-3 hours, but sometimes she only eats for 5 minutes) To counter my new found time awake during the night, we decided to try getting her to sleep a bit earlier. Coincidentally we also noticed that she was getting more and more fussy earlier in the night, so we proceeded to start the same routine (lights, sound) at around 8:30. So far so good. It seems like she is getting used to sleeping at this time, and doesn't require that much coaxing (i.e. nursing,rocking etc.)
The main thing I can tell you is don't get too set into a particular time, because as your baby grows and develops it will all change, and as all babies are different it's hard to predict. Just listen and pay attention to your baby and experiment with what works best and you will figure it out. Good luck!!