Botox for Chronic Headache?

Hi everyone!
I've had a headache since March and tried many different treatments with no success. I'm going to Jeff and they tried Botox today. I was aware that this was a treatment for migraine but had not heard of it for New Persistent Daily Headache. Any have experience or success with this? How quickly does it work? How often do you get injections? Is it covered by your insurance?

Thanks,
Amanda