Somewhere around the 3rd or 4th month you will more than likely make the switch from the bassinet to the crib. For Mario it came at the beginning of his 4th month. You will know when its time. Some of the signs will be your child is growing too big for the bassinet or they are beginning to fuss and move around too much in their bassinet.
It is very important when you move them to the crib to make sure you do not keep blankets or anything else they can choke on in the crib with them. Keep the room at a temperature you would sleep at. During the summer months make sure you baby is in relaxed clothing and nothing that will make them sweat. Infants retain heat as it has no place to go. This could lead to febrile seizures. So make sure they are comfortable.
Once they are in their crib around the 4 month mark its gonna start taking them awhile longer to fall asleep. they are going to be looking around and listening to the sounds in the room. It is best to get a mobile for the crib. Something with soothing sounds.
For Mario we had the mobile going along with a night light (that was on the baby monitor). As they get older it will become harder and harder for them to go to sleep. They will want to stay up and will crave your attention. So you will probably be adding things to their room. You must get the child in a routine. Have them start going to bed at the same time every night. Our bodies have an internal clock. I don’t know about you but I wake up at the same time every day for work. I normally wake up a few minutes before my alarm goes off. Babies are the same. But they are developing that internal clock. We as parents have to help form those routines.