How long does it take for swelling to go away after hctz (hydrochlorothiazide) for pedal edema?

Depends on cause. Dr. Lizarraga makes an extremely important point. There are certainly causes for pedal edema that diuretics (like hctz) won't help. Varicose veins with venous insufficiency and, especially, lymphedema are two of them. Because there are so many causes for foot and ankle swelling, finding out what the real cause is and then successfully treating it can sometimes be quite difficult.
Maybe never! Because there are many causes to swelling, the swollen feet may not go away with a diuretic. If they do, i would expect a response within 2-3 days, and that you would have seen a maximum effect by 2 weeks.