How much time after PRP injection should be taken after first PRP sitting?

The research performed and the anecdotal evidence would suggest that thickness of hair and density can improve with PRP injections.  The number of sessions as well as the quality of PRP obtained will vary considerably physician to physician.

Thank you for your question about PRP hair restoration.  I cannot speak for all offices, but our office recommends at least three sessions of PRP injections 4 weeks apart. To be sure, see two or more experienced, licensed and board-certified providers in your area for a complete evaluation to make sure you are a good candidate and that it is safe for you to have treatment.

I hope this helps.

A study presented at the American Society for Dermatologic Surgery meeting tested this particular protocol issue. It was found that monthly injections is superior to injections every 3 months at the initial PRP treatment.  The higher the concentration of minoxidil, the better the results provided that you do have the minoxidil sulfotransferase enzyme. A direct comparison between dutasteride and finasteride has not been done. Both are effective. Find a PRP expert. Ask to see photos.
PRPHAIRMD.COM 

It can take 4-6 months before most
patients notice improvement in their hair thinning.  Patients in our office have reported a
decrease in shedding as early as 4 weeks after their initial treatment but
results can vary.

Our protocol is one PRP treatment every 5 to 7 weeks for a total of 4 to 6 treatments. 
5% Minoxidil should be enough. Keep in mind, that though Minoxidil is a topical, a portion of it can go systemic. Therefore, should you go to the higher dose you should be aware of the possible side effects and adjust as needed.
In regards to Finasteride or Dutastride, along with a physical exam I prefer to do some lab work before I go to either medication and see what the root cause of the hair loss may be. Generally, the culprit is simply DHT. Sometimes it can be more complex.
If I unlikely failed to treat the root causes more naturally first and if indicated for the individual, my preference would be the Dutastride. It caries the lesser of possible adverse side effects.
Hope I have helped.
Warmly,
Arbella Sarkis, MD