First of all, relax men, we all felt that at the start. In my personal case I did relapse twice after my reboot. That 2 times were after a week.
Now im on the good reboot one. Last week i did 2 months, so listen:
So, my advice and my experience tell that the first 2 weeks are the worst ones. I actually also felt that I could not reboot and stop masturbating and watching porn but its all in your mind bro. Just relax and keep it controlled. You must understand is a long process, so do not despair, and, if you feel the need to masturbating or watch porn think about how frustating is stay in front a beautiful girl that is desiring to have sex with you and you can not because you cant get erected.
Once you pass the first 2 weeks you will feel really really relaxed, you will start feeling happier and you will not have the need to watch porn or masturbating. Even you start avoiding it because you know is not what your body wants.
So bro, stay strong, especially the mind. The mind is what controlls all.