Most babies sleep patterns are erratic for the first six to twelve weeks. You would be extremely fortunate if you see a pattern before this. By three or four months though, if you are consistent and positive, you can help your baby into a regular sleep pattern.
Babies are quite adaptable. Your baby can be taught to sleep in your bed or his cot. With or without you, the choice is yours, but you are likely to stick with a plan that feels right for you.
Every time he wakes during the night, repeat whatever you did to help him sleep for the first time. If you feed him to sleep, then baby will need you to do the same every time they wake up. If you leave them alone to sleep, then they will expect to be left alone.
There are only two essentials for whatever plan you decide to use. Firstly, once you begin a plan of action, see it through. Don't give up after trying something for forty-five minutes. You will have simply taught him that it is worthwhile to persist for as long as possible (babies can be very persistent).
Give your plan a chance to work; stick with it for at least a couple of weeks. Don't disrupt it for night out or a holiday. Each new plan means that baby has to learn a new set of habits. Old habits take time to break and new habits need time to develop. Don't confuse your baby by frequently and haphazardly changing their routine.
Your baby will be comforted into sleep by a predictable and restful bedtime routine. They will also be more likely to sleep if you try to avoid letting them nap in late afternoon.