An earlier diagnosis of autism spectrum disorder might lead to an earlier intervention, yet knowledge and awareness of autism spectrum disorder in Latin America and Caribbean Countries are limited. A later autism spectrum disorder diagnosis has been associated with negative consequences, as it might imply later access to services. This study aims to identify factors associated with the age of autism spectrum disorder diagnosis as reported by 2520 caregivers of autistic children from six Latin America and Caribbean Countries. Results indicate that on average, caregivers were concerned about their child's development by 22 months of age; however, the diagnosis was 24 months later. Current age of autistic individuals, better language abilities, and having public health coverage increased the age of diagnosis. On the contrary, the presence of medical comorbidities, severity level, and type of diagnosis decreased the age of diagnosis. The age of diagnosis of autistic individuals in Latin America and Caribbean Countries corresponded to the start of formal schooling despite a much earlier age of first noticed developmental concern, highlighting the need to reduce this age gap and increase children's probability of benefiting from early intervention. Taken together, autism spectrum disorder personal/clinical characteristics and access to health service are the main determinants for the age of diagnosis.