The very earliest thing I can remember is from before I was 2, and it is not traumatic. It is just an impression of a visual snapshot and a moment of understanding. Some say you don't form lasting memories until you have the language to code them but this obviously doesn't include traumatic memories which are encoded as sensory flashbacks rather than verbal narratives. This narrative memory, short though it is, is not traumatic in any way.
My earliest traumatic memories are from age 2. From then on it's a bit of a mess.