0 to 2 weeks. You can return to walking and low impact activity right away as long as you feel up to it. Listen to your body and don't exercise if you are feeling too sore or fatigued. You should not do high impact or abdominal exercises for at least 2 weeks if you had a laparoscopy (small incisions) and 6 weeks if you had a laparotomy (large incision).
Ask your surgeon. Ask your surgeon for specifics. Once you are fully healed you should be able to do any exercises.