Penelope Leach defines the "settled baby" phase as beginning after the first month. Her book, Your Baby And Child, has been around for awhile. I recall seeing it sitting around the house when I was young. I actually read the book during The Boy's baby phase. Anyhow, the implication is that a baby is unsettled during the first month. I'll agree.
So much of that first month is just trying to figure out what the baby wants and how he wants it. Cracking the code, if you will. The Boy: semi-predictable feeder. Loved the front-pack carrier. Loved the car. And rocking chair. Tiny Guy: slightly more settled in his eating but still always hungry. Loves the sling. Beginning to tolerate the car. Loves the sunshine. And walks outside. Loves being naked. The Boy didn't until he was older.
It takes time to figure things out. And then they change. Children get older, too, and the decoding process continues.
Same deal with toddlers. And eleven-year-olds. Except that toddlers talk a little bit. And eleven-year-olds talk a lot. Sometimes, it makes them easier to understand.