From the moment your baby is born, it makes sounds and the pioneer of them is crying: there starts the process of communication. This stage is defined as Pre-linguistic, considering the phonic level that is all the sounds that it emits from the "gu-gu, ga-ga" until it says its first word, usually "dad", right? ...
In its evolution, various signs appear month by month, becoming clearer and clearer, allowing us to verify that the language is in perfect development. Around 6 months, they begin to articulate the monosyllabic ma / pa / ta / ba.
And so, little by little he continues to evolve until he manages to vocalize the first word, between 10 and 12 months, giving way to the Linguistic stage where he will begin to express himself verbally through words and phrases with meaning.
It is difficult to delineate the boundary between the "normal and the abnormal" in language. This is not acquired with the same rhythm in all infants and what in some cases can be considered as a simple delay, in others it is a sign of difficulty that deserves more attention.
The time to occupy yourself in detecting if something is not right with respect to the subject, is between the ages of 3 to 4 years. At this time, the child should perfectly develop the pronunciation of words containing consonantal phonemes b / r / j / g / p. If not, it is advisable to request a professional assessment.
And remember ... when the existence of any alteration of the language is already known, it is convenient to treat it before entering the first grade of primary education, so that it does not hinder the learning of reading and writing.