-- The Important Early Autism Signs in Infants Every Parent Must Know. br The early autism signs in infants start to appear as early as six months but typically infants are diagnosed only upon reaching 3 years old.It is important for parents to be aware of the early autism signs in infants. br Early identification is important so that interventions can be implemented and parents can also seek advice and help from experts and from autism organizations. br Here are the 4 early autism signs in infants every parent must know: br -Unusual interaction with others br -Lack of interest in the surroundings. Several studies conducted showed that babies with autism react differently when confronted with certain situations. br -Infants with autism often have difficulties controlling their emotions.