The title links a long NYTimes article on finding autism early. I know several families with autistic children and anything parents can do to find it early can only help.
The article refers to www.firstsigns.org which has an easy-to-use screening test that can be used as early as 18 months. Please explore the site and read the instructions to use the CHAT (Checklist for Autism in Toddlers) and M-CHAT (modified CHAT) tests.
As always, if you are concerned about your child with any development issue, please speak to your pediatrician or specialist.