Background/Objectives: Early diagnosis of autism spectrum disorder (ASD) is a very important factor for improving the quality of life of people on the spectrum, but it still remains a major problem in Europe, especially concerning girls. In this study, we tried to answer the question of what factors affect the age of diagnosis in Poland. Additionally, we tried to establish the time between the first visit to the mental health center (MHC) and the diagnosis in this population, and what factors affect its length. Methods: 77 children were randomly recruited among the patients who came to local MHC at the Child and Family Health Centre in Sosnowiec. All participants were tested using the ADOS-2 protocol. In addition, the study used the TAS-20 test and BDI. Results: The mean age of the first enrollment in the MHC was 9.09 years for girls and 6.42 for the boys. The time needed to obtain a diagnosis from the first visit was consecutively 2.90 years and 4.29 years, but the difference was not statistically significant (p > 0.05). Obtaining a different psychiatric diagnosis did not affect the average time to diagnosis and the age of diagnosis. Conclusions: The results of the study indicate that the diagnosis of ASD is still a significant problem both in Poland and in the world. Obtaining an accurate diagnosis requires significant time, and it frequently involves consulting multiple specialists. The diagnostic process should be flexible, and the specialist should always take into account the axial symptoms but remain aware that the “overdiagnosis” of ASD can also have harmful consequences for the child.