Im on week 7 of my cycle and I didnt take any arimidex till week 4 of my cycle, and only started once I started having sore nips...Once I had soreness, I ran it at .50 for 4 days, then .25 every other day after...I will take it throughout cycle+throughout pct to keep estrogen from rebounding...I have heard many schools of thought on taking it, some say start day one of cycle and throughout, others say start when symptoms occur...I dont have estrogen issues so i waited till soreness began and then nipped it in the butt..Prob could have gotten away with not taking it at all, but better safe than sorry...Make sure you have nova on hand, if arimidex doesnt do the job, and run it for a few days to stop estrogen...