How long does it take for the square/box shape to fluff out after a BBL? How long does it take for it to form?

Final shape may take 3 months or more to develop.Kenneth Hughes, MDBeverly Hills, CA..................

Hello dear!!
Thank you for the question and provided information as well.
The healing process could be from 6 months to a year, depending on the patient. The inflammation and bruising could last months. If you have any concerns, I suggest you follow up with your plastic surgeon.
Be patient, it is too soon to determine your final result.
Good luck :)

It takes 3-6 months to see the final product as a portion of the injected fat volume is lost over time (~30-50%). The overall shape does not change drastically aside from shrinking in size. If the buttocks look really square immediately post op, they aren't going to look round and protrude more later. The curves may soften with time.