How long should I wait to workout after an abdominoplasty & lipo?

Ask Surgeon. Your plastic surgeon will be your best resource; he/she will know you are progressing and what activities you wish to return to... Best wishes.
Listen to surgeon. While each surgeon is different, i would certainly hope that my patients would follow the directions i give them. After a tt with muscle repair, i tell them that they can return to the gym after 6-8 weeks for non-abdominal exercises. Abdominal exercises and sports that use a lot of core strength, (golf, tennis, yoga, etc.) we wait ti 3 months post-op before resuming. Lipo without tt: 3 weeks.
Let your body guide. The easy answer is to "let your body be your guide": if you are back working out too early, you will have swelling - your body telling you to reduce workout intensity. I provide a compression garment to wear after liposuction that helps reduce any swelling and allows a return to activity more quickly. I like my patients to start walking the day after surgery but delay any workouts for 3 wks.
2-8 weeks. The answer really depends on the extent of the abdominoplasty. Small abdominoplasties involving merely some skin and fat removal would require minimal cessation of activities--maybe 2 weeks or until cleared by surgeon and you are feeling well. Large abdominoplasties involving muscles should probably wait at least 6-8 weeks.
Working out. Your surgeon will recommend when you should return to exercise. It is important to follow your postoperative instructions as the surgery that your particular surgeon performs may require more or less recovery time.
About 6 weeks. If everything goes perfectly. If the muscle is not repaired i let people start working out sooner but usually i tell patients not to run or do vigorous exercise for 6 weeks after abdominoplasty and 2-3 weeks after liposuction alone.