I would say an early sign for both autism and aspergers is little or no eye contant when speaking to someone or when being spoken to.
Little or no speech.
Playing with toys inappropriately. By this I mean that they may have no idea what to to with toys eg. turning cars over and just spinning wheels.
Hand flapping, walking on toes all the time, making lots of strange noises, extreme sensitivity to sounds, fabrics etc.
There are lots of early signs for autism but each child is different and therefore, they all show different signs. I hope this is helpful to you.