How soon after BBL can I sit fulltime without hurting my graft... like 5 hrs Straight?

I recommend minimal to no sitting for the first 6 weeks after surgery. After six weeks, my patients can sit unrestricted. Please consult with your surgeon. 

Hello dear!!
Thanks for the question and provided information as well.
Each doctor has their own protocol It is very important that you talk to him about your concerns and goals. I recommend my patients not to sit for more than 30 mins. every two hours, for the first 2 weeks, and always with the help of a boppy pillow. If you have any concerns, I suggest you to follow up close with your plastic surgeon.
Hope this is helpful. Good luck :)

I usually have patients wait about 2-3 weeks, but every surgeon is different and you should ask your surgeon directly.

My patients leave the operating room sitting on their back. I find hard to instruct patients to lay otherwise. However, you have to exercise your judgement and consult with your surgeon.Generally, I let my patients drive freely in 2 weeks and resume unrestricted activity in 4 weeks. I tell my patients to discard the garment at 6 weeks and to expect their result from 12 weeks onwards.

I would avoid sitting as much as possible for the first 2 to 3 weeks following a Brazilian butt lift.  At three weeks it should be safe to sit for several hours.  However, I would suggest you get up and move around every hour or two.  If you are still wearing a compression garment be certain to straighten it out when you get up.  Best wishes.