My 16 month old son is waking early every day between 4am and 5am. His cot is in our room still because we have two older children and my wife and I have tried all sorts of things to try and get him to sleep longer but without much luck. He was a fabulous sleeper as a baby but now even on the darker mornings he is waking early.
tbh though, that is a really early time to be putting such a young baby to bed for the night. Not that it can't be done, but it is unusual for them to be able to go that long without needing something to eat or drink or even a bit of a play.