Baby smiling?

Hi there!

I’m just wondering when everyone’s babies did a social smile for the first time.

My baby has done only a few not very big smiles to where it’s hard to tell if it’s an actual smile or gas or something else and he is 8 weeks old. When we went to the doctor she seemed kind of concerned about this and suggested there could be an issue with his sight or even autism.

Just looking to know when babies started smiling and when they started smiling all the time.