8 to 12 months—It sounds like speech but it’s really ECHOLALIA to me.
You may say to the baby of 8 months, "Daddy’s coming…" and the baby may reply, "Daddy coming…" It sounds great but in most instances it is just a fancy bit of jargon in which the child has put the phonemes in the "proper" order.
It is a sign of some good eidetic imagery and a well developed mixer, but there is no semantic content involved. The child has no concept of meaning of the words "daddy" or "coming" let alone the significance of the two word combination. Although it is a step above jargon, it is not yet speech and language.
This occurs a lot with older nonverbal children who are progressing through the milestones of speech at a much slower pace.
They will often fool us (not purposely, of course) into thinking they have reached that symbolic milestone when they in fact haven't quite made it yet.