Can you tell me how much time does it take to make a proper autism evaluation?

Difficult question: A "proper" evaluation can be done within a very short period of time if the autism is severe. If it is not severe however it may take specialists from a number of areas to definitively determined the diagnosis. Critical is what the clinician sees during the evaluation. The diagnosis can be difficult if seizures are involved or mental retardation or other comorbidities such as attention deficit hyperactivity disorder.A very straightforward case can be diagnosed in an hour interview. Others will take multiple interviews, the gathering of a lot of collateral information from school and from home and from teachers, and possibly neuropsychological testing.Best wishes.