You can train your baby to sleep within two to three weeks. There are different ways to do this; however, the purpose is always the same. Your child should be able to fall asleep on his/her own in the crib.
Some parents prefer the tougher way of achieving this goal. So, they put their child to bed and keep checking on them at frequent intervals. How many times you check on them during the night is totally up to you. With this approach, most parents can see an improvement within three to five nights.
However, some parents prefer to take it slow. So, here is how the slower approach works. Put your child in the crib and sit next to it until the baby falls asleep for three nights. For the next three nights, be in the same room but not next to the crib. Slowly move on to the doorway and then to the hallway.
Don't wait to check on your baby unless they begin crying. If you do this, your baby is going to learn that if they scream loudly, you will come running to them. While checking on them, reassure them and leave. Don't worry about sleep training in the middle of the night.
Most babies will be sleep trained within two to three weeks and they will begin sleeping throughout the night.