In my experience, nerve blocks take several days to kick-in. Yes, the injection is painful and can knock you out for a few days. I had three nerve blocks before I decided it was not worth it to me to have steroids in my body. CGRP's have been more effective for me. I take Aimovig 140 every 28 days. I am on my second round of Botox and still have not decided if that is beneficial. Botox does us CGRP's which are proven to reduce or mitigate headaches. I still have daily headaches, they are just more tolerable. My tumor is inoperable. I hope this information helps. You are not alone.