For me, cravings came in waves. When you're feeling good you can get a bit cocky, and the hard cravings catch you off guard because you worry that maybe you weren't making any progress. The truth is that you ARE making progress, but your porn addiction is like an army that retreats and comes back with reinforcements; ultimately it means that you're winning, but you need to be ready for it.
The other side of it is that if you're in the midst of a hard craving phase, you can know that if you ride it out, it will get better. Where the craving can really trick us is to make us think that a relapse is the only way to relieve the pressure, but it is far from the truth. Ride it out, don't fall for the traps, and once you're on the other side of it, you'll feel a lot better.
Something to look forward to: In my own non-professional opinion, this is when the reboot happens. When the addiction is attacking us and we fight, that is when we're doing rewiring. When we're just sitting still and feeling okay, we aren't rewiring that much. So, if you're sweating it out and feeling awful, remember that the feeling is you beating the hell out of your addiction.