1 night in the hospital (occasionally home the same day)
Walking the day of surgery
In and out of bed, in and out of a car, up and down stairs- immediately.
3-10 business days off work. People who work desk jobs can return earlier than those doing manual labor
5-7 days of no driving. He can return to driving when he does not need to take prescription pain medication during the day, and when he feels comfortable turning from side to side.
Strenuous activity (sports, weight lifting, sexual activity) about 2 weeks, but ultimately whenever comfortable
About 80% recovered at 2 weeks.
Full recovery, meaning appetite and energy return to normal and vague aches and pains of surgery go away, may take about 4-6 weeks.
I am going to assume that your son's appendix was not ruptured. Because there is slightly more pain with the regular incision (#1) and it may take 1-2 days to be discharged from the hospital. Because of the incision, children's sports or other vigorous physical activity is usually limited for around 3 weeks.
If the procedure was done by laparoscopy, frequently children can be discharged from the hospital the next day. Also, because there are only 3 very small abdominal incisions the physical activity restrictions can be significantly reduced. Regardless of what procedure is performed, the children are usually back to normal in 1-2 weeks. I hope this helps.