There are really two separate risks here, and they peak at different times. The first is fat embolism — fat entering the bloodstream — which with a BBL is an early event, highest in the first 6–24 hours and mostly settling after the first day or two. By day 7 that window has largely passed, and importantly it isn't something blood thinners prevent; it's avoided by careful surgical technique during the operation itself. The second is a blood clot in the legs (DVT) that can travel to the lungs. This is the one that matters for your flight. After surgery this risk peaks around days 3–4, stays relatively high through about day 7, and can still occur any time in the first month. A long flight adds its own, separate clot risk on top: sitting still for nearly 20 hours, dehydration and cabin conditions all slow the circulation in your legs and thicken the blood. So the issue isn't really day 7 by itself — for someone recovering quietly at home, a week out is often fine. The problem is stacking a 20-hour flight onto a body that's still in its highest-risk clotting window after high-volume liposuction and fat grafting. That combination is what makes it risky specifically for you. My advice is to wait at least two weeks before a flight this long, and to travel with compression stockings, hourly walking and steady hydration once you do.