How Long to Wait Between Surgical Cosmetic Procedures?

I do not want to come across as unfeeling, But are you serious? Going to 2 differing doctors within 4 days is and sounds NUTS! I'm sure you have not told either one you are planning this course of action. Have you? If I was either one I would excuse myself from your care. Please be careful but maybe you need a reality check.
From MIAMI 

First of all, I would agree with the surgeons who stated that most Board Certified Plastic Surgeons are capable of performing both the liposuction breast reduction and fat transfer to the buttocks, and it makes the most sense to both at the same time. This way you are not wasting any fat that is being aspirated, and you can have one surgical procedure.
That being said, it appears that you seem convinced that you will get better results by having 2 different surgeons perform the procedures. Have you asked them if they could coordinate your surgery so both could be done at the same time?

If you are healthy, there is little risk to having two surgeries several days apart, but I am confused, why are you going to two different surgeons, and why have you chosen liposuction as your breast reduction technique? For many reasons, this is not a standard approach to safe and aesthetic reduction in breast volume. Most, if not all surgeons certified by the American Board of Plastic Surgery can and do do breast reduction surgery. Not all have adopted fat grafting to the buttocks as a commonly done procedure, also for a variety of reasons. However, you should be able to find one surgeon who is experienced with both procedures; it should not be necessary to have two different doctors for this surgical combination.