How long do I have to wait to sit on my butt after an awake BBL?

Every surgeon has a different recovery protocol so it is best to talk
with your plastic surgeon about what he/she recommends for you. With
that said, short answer is 8 weeks. I advise my patients not to sit on
their rear ends at all for the first week, this includes driving. After
then they may sit for short periods of time with a pillow under your
legs above the knee for 8 weeks, it doesn't have to be a special BBL
pillow if you don't want to draw attention to it. I would not recommend
sitting normally without a pillow or sleeping on your back/butt for 8
weeks. 
Kamran Azad, MD, Board Certified Plastic Surgeon@kamranazadmd

Best to ask your plastic surgeon for his/her recommendation.  I recommend that my patients minimize sitting, even with a pillow (boppy or BBL), for the first two weeks.  If they must sit, every 30 minutes or an hour, they should get up and stand for a few seconds to take the pressure off.   This reduces the chance for fat necrosis. I usually recommend about 6 weeks before sitting without a pillow. After 6 weeks the fat has revascularized, and they will have a very good idea of their final results.  Kenneth Hughes, MD, ABPS Board Certified Plastic SurgeonLos Angeles, CA