The point isn't to have no carbs, but to limit your intake to a minimal amount. I personally on occassion do have a small amount of carbs after a workout and can still maintain ketosis. Just need to find your balance. It's different for everyone.
I'd say no more than 20g while in your first 5 days then increase for your carb up days. There's a great thread in here somewhere but I can't find it right now...I'll keep looking.
The thread broke down the ketogenic diet by daily percentages and helped to figure out your BMR and AMR in order to calculate daily caloric intake.....it also talked about Phenyltropic PPA....anyone know which one I'm talking about?