How long will the redness and swelling on my hand and feet last (i'm at 24 weeks)?

Depends on the cause. Redness ad swelling on the hands and feet can be due to a variety of different reasons. Have your self evaluated by a professional.
Until after delivery. If you already have significant swelling, you can expect it to continue until a couple of weeks after delivery. It will probably vary from day-to-day, depending on diet, activity level and weather. It will generally get worse after delivery for a few days and finally resolve 2-6 weeks after delivery.