What is behind each of these opinions on when to get PRP after hair transplant?

Greetings. I wanted to clear up the PRP issue once and for all. I have seen a lot of opinions on the timing of a PRP injection after a hair transplant. Some doctors recommend doing it ten days after the transplant. Others recommend doing it after three weeks. And others (which are the majority of what I know) recommend doing it two months after the transplant. What is behind each of these opinions? After all, the timing of the PRP injection is the most important to get good results.