How soon can I return to water aerobics class, 1 hr in pool, after my appendectomy on aug 18th. Stitches out on aug 25th. Healing well.

DEPENDS. If this was laparoscopic surgery, you can return to full activity in 10 days. If you had open surgery, you'll have to wait 3-4 weeks before you initiate strenuous activity. You do need to clear this with your surgeon. Good luck.
2 weeks average. Our skin heals within 48 hours. That being said, different wounds heal differently and on a unique time frame for each individual. As a general blanket statement, 2 weeks after your surgery without any wound healing issues is an acceptable timeframe. You should of course consult with your general surgeon for the final answer.