When is the soonest fat cells can vascularize following a facial fat transfer?

Fat grafts (live fat cells and stem cells) receive new blood supply from the surrounding tissue and its blood vessels. Multiple new vessels are formed and they grow into all areas of the grafts. Those areas close to the surface are receiving new blood supply first while deep areas are very likely to stay without blood supply and will die. It takes at least 6-8 months, possibly longer, to see the result of fat grafting. It is still unknown whether that depends exclusively on fat cells survival or numerous stem cells present in the fat grafts are able to produce additional fat cells. Hope this helps.