First of all, I commend you for looking for advice and looking into reading more about Asperger's Syndrome. I work with lots of these children. Many times at your son's age, they give the dx of PPD-NOS or Autism Spectrum Disorder before they label as Asperger's... but that might be changing these days.... the thing is, as his parent and the doctors as the professionals who see these children regularly, I believe Asperger's is definitely detectable this early on... so I think you are doing a great job in "treating it" as such until you get a more definitive answer.
My biggest recommendation to you is to prepare your son for events to come. Picture schedules work very well to help reduce anxiety about daily activities, what to expect, etc. Some people use real pictures to represent objects and activities, and some people use Mayer Johnson Picture Symbols (the program is expensive, but very useful). I think all children could benefit from these - not just children with Asperger's Syndrome or ASD, but it's been known that children like your son understand much more when presented with visual stimulus vs. just auditory. It might be something as simple as a "first / then" board. First, "school", then "grocery shopping". Whatever it might be. Or smaller steps to help him complete tasks such as the steps to getting dressed and picking out clothes or brushing his teeth independently. Not sure what your child needs.
Remember that children with Asperger's are very bright children - but have most difficulty with social appropriateness and skills to function with peers as well as adults in an "accepted manner that society conforms to". It's not unusual for a child with Asperger's to blurt out an inappropriate thought or to publicly pick his nose or reach into his pants to adjust... these children learn best by hearing or seeing DIRECT and EXPLICIT examples. Figurative language or assumptions cannot be made - as it is completely misunderstood by them. They will not "pick up" socially acceptable behavior by just observing and watching and learning by trial and error (well they do, but it takes a lifetime) or from other people's facial expressions. They need to be TOLD, "Johnny, it's not appropriate to pick your nose in front of other people. It makes people feel uncomfortable because it's yucky". and then give an alternative: "If you feel you need to pick your nose, excuse yourself by saying, "I need to go to the bathroom (even if you don't have to use the toilet), and you can pick your nose in there where it's private, and then wash your hands when your done." Something to that effect. Direct, and no beating around the bush!
That's just the tip of the iceberg of course... but keep doing your research and asking questions. Your son will do great with such a good advocate!
I listened to a wonderful audio book - "My Life with Asperger's" and it's narrated by the author, John Elder Robison. It gives tremendous insight into how these people perceive things and events around them - a first hand account! I really enjoyed it.