With my baby I did some sleep training with him. I feel it's best to have babies in bed around 7 pm. Watch for any tired signs and put her to bed. My baby goes to bed around this time and sleeps almost 12 hours at 5 months old. This is due to the sleep training I did with him around 4 months of age. It's harder on you than it is the baby, but will benefit everyone in the long run! My baby was waking every hour to eat at 3-4 months of age and it was taking a toll on me and not allowing me to enjoy motherhood. Helping my baby learn how to sleep through the night was one of the best things I did for both of us.
If your baby is waking for milk it has probably become a habit. At around 4 months of age babies don't necessarily need to wake for feedings multiple times during the night. My baby will wake on occassion and be hungry, but this is getting more rare.
Here's some hubs I did on what worked for me in getting my baby to sleep.
Good luck and hang in there!