How many inches am I expected to lose in waist and gain in hips after having a BBL? My measurements are 34 32 41

This is impossible to answer without an exam.  You would need the maximum of 5 liters removed from around the waist to get at least a 4 inch reduction.  
The final shape of the buttocks is largely determined by the starting anatomy, the distensibility of the tissues injected, and the surgical skill employed by the plastic surgeon. Significant volume can be added to the buttocks, producing much larger, more projected buttocks. The fat is expertly placed to produce very shapely, custom tailored buttocks.  Even large defects in the buttocks or marked asymmetry can be remedied with this fat transfer technique.
Certain aspects of the buttocks or hips may not be improved as much if the tissues do not allow for much stretch or cannot accommodate the fat that is transferred. In these cases, the final result will be limited by the skin envelope. This is an issue that cannot be completely controlled by the surgeon. Finally, the ability of some patients to heal and retain more of the fat than another patient accounts for differences in shape and result following BBL.
Ask these question of your board certified PS who will perform your 360 BBL in about 2 weeks.

Thank you for your question. To provide a valid medical opinion I will need to see pictures of you body from different angles. I would suggest to be treated by board certified plastic surgeon with experience in this procedure, to get the best desired results.
Respectfully,Dr. Emmanuel Mallol Cotes.-

It is incredibly difficult to answer your question without photos or a consultation. Secondly, you should expect to gain and lose as much as was discussed with your board certified plastic surgeon. An in person consultation should have given you the chance to tell your PS your cosmetic goals and create a plan. A Skype or FaceTime consultation with a board certified plastic surgeon will help you get an accurate recommendation for your procedure. 
Respectfully, 
Arian Mowlavi MD, FACS
Realself 100 Hall of Fame Inductee