So you're pointing out that your son is struggling to manage his time well, and you would like to help him do that more effectively so he is able to take care of his responsibilities and enjoy himself. I think that until he is able to manage his time better, you may want to operate as a "temporary time management assistant" for him (you may already have thought of this). In other words, remind him how long a chore took the last time he did it, help him plan how long he needs then to give himself, what time he would need to start the chore if he has something scheduled afterwards. And then see how it goes.
I guess it's just a matter of what I think is common sense, and he has absolutely no clue. He seems unable to judge how much time is needed for activities or chores, leaving himself an inadequate amount of time before his next activity.
For example, if he has a show on tv he wants to watch and he knows that he must complete a chore before that show is on, he doesn't leave enough time to accomplish his task and he is genuinely frustrated that he didn't.
I am sure he isn't trying to get out of doing chores (he has different tactics to accomplish that!).
I think what you're asking about is how and when children learn about time management. Can you be more specific, what is the issue is with your child regarding time management?