FWIW, that progression is considered to be a bad idea. Children learn by imitation. Making noises and speaking in nonsense words to them certainly does not help them, and may actively set them back. You should start out right at stage 3 of your progression: correct use of language with simple grammatical constructs and vocabulary.
Its no coincidence that this is also the way to help an immigrant learn the local langauge quickly: no pidgin, just speak a little slower so that they can follow.
(In fact, experience with parents teaching their babies sign language provides evidence that babies have linguistic skills pretty much from day one, long before they learn to speak. See some first-hand experiences.)
Makeshifts last the longest.