How soon after giving birth can I get a double mastectomy with immediate DIEP reconstruction?

The time frame for your mastectomy will completely depend on the opinion of your obstetrician and breast surgeon. These two providers can determine the best timing for your mastectomy that will allow you to heal since giving birth and based on the urgency of the situation. As far as immediate DIEP reconstruction at the time of your mastectomy, this will also depend on timing and your diagnosis. Depending on what your diagnosis is and the opinion of your reconstructive surgeon, it may or may not be feasible to perform this at the same time as your mastectomy. I am sorry I can’t be more specific but your situation does depend on multiple factors and providers and it is safest for you to get their individual opinions. Best of luck!

Dear Considerate8780,
you should be fully healed prior to surgery. Most plastic surgeons will recommend you to wait at least 6 months. If you are considering a surgery, I would suggest you to consult a board-certified plastic surgeon. Only after a thorough examination you will get more information and recommendations.
Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

DIEP flap surgery should be done after weight is stable following delivery. In addition, it should be done months after breast feeding cessation.

This is a tricky question.
Are you having your mastectomies prophylactic ally (no cancer) or because of a present breast cancer?
If you currently have breast cancer, I would recommend a mastectomy as soon as cleared from your ob/gyn. You can have tissue expanders (water balloons) placed at the time of surgery in order to allow your body to heal from the pregnancy and return to your pre-pregnancy weight. You can then have your DIEP surgery after you finish your cancer therapy (radiation, chemo, etc).
If you are looking to have bilateral mastectomies prophylactically, I would wait at least 6-9 mo until you are back to your pre-pregnancy weight. If you have the option, its best to try and complete your family before having DIEPS, as a pregnancy after a DIEP will be uncomfortable as you are re-stretching skin. 
Please see a board certified plastic surgeon in consultation.