How long does it take for Voluma filler to settle in cheeks, so it won't be able to shift?

I want to get Voluma filler in cheeks the day before my buttock implants surgery (Clinic far away). I'll have to lay on my stomach during and after the surgery, which means pressure on the cheeks, with my face on the pillow. I'm wondering, how long does it take for the filler to settle, so it's safe to say it won't shift or distort anymore? I'm worried I might lay down for a long time on one cheek, so pressure will be on the other side of the face, and the result may end up being asymmetrical.