At this stage your child is able to grasp basic awareness of time. From kindergarten, he would have started grasping about the concept of time, but it becomes more fine-tuned when he is in this current age group.
What you need to know
At this point you should know that learning to read a clock is a pretty tough concept for your cutie pie. He will take years to understand this concept but he will definitely be able to grasp it. Initially you can introduce the concept of time to him by his daily activities like it is breakfast time, lunch time, bedtime and so on. Once he starts to grasp these concepts you can divide it as morning, afternoon and evening. You can tell him “It is afternoon nap time and in the evening we shall go out to play in the park.”
Once he is in the first grade, reading words and recognizing numbers will become easy for him and so understanding the concept of time will be easier. You can give him a less expensive non digital wrist watch to encourage him learn time better.