While I am not sure what exactly the OP is doing a cycle of....it is usually a waste to run during ANY part of the cycle as cortisol is already suppressed with the rise in exogenous androgens. It may be better to start it at around week 2 or 3. There are adrenal reasons for this that I have read, but without the data right here I won't spout too much on that. I, personally, have used them Day 1 of PCT, 2 weeks into PCT and not at all. The results were all pretty much the same. That is just me though. I do have to say though, that as far as products, I love me some PP Endoamp. This is an amazingly cost effective supplement for what it is and and it has numerous benefits.