From my experience:

Keeping an exact time from when you last cut is a bad thing. Then you go "But I haven't cut in 2 days...so it's okay now, because I went so long without it." or "4 days longer than last time - I can do it. So now I deserve it."

I just try and go as long as I can without it, surpress the urges as they come, and distract myself. It's almost like being an alcoholic: One day at a time. You're doing great, don't forget that. Also remember the ice cube trick (hold on against your wrist) or draw a red line on a part of your body. Scream. Yell. Allow yourself to let go and not hold it all in, throw a temper tantrum and throw yourself to the ground like a 4 year old.

Just don't cut, cause in the long run, it's not worth it. And we both know that.