This seems to be a common question lately. YOU ALWAYS NEED AN Aromatase inhibitor (AI) FROM DAY ONE! I will debate this fact with everyone! I think sometimes we get more focused on repeating what we haveheard a 100 others say on here instead of sharing actual knowledge!
AI's fight estrogen build up, not gyno. Gyno is ONE side effect of high estrogen. Limp dick, not reaching orgasm, sleep problems, high blood pressure, and water retention are just to name a few of the side effects of high estrogen. You run an Aromatase inhibitor (AI) to combat high estrogen. Everyone reacts to high estro in different ways. Do not wait for sensitive nipples to combat estrogen. Because of conversion, your estrogen is going to be high. You need something to combat that.
Somewhere along the way we have began to confuse AI's as anti-gyno meds. While this is indirectly true, it is very deceiving to the new user like yourself. Research what AI's actually do. Better yet, look up what effects high estro can have on your muscle building!
Like China said, why wait for something to have it. Take it from day one and prevent. In addition, 98 percent of the weight you gain will not be water! It gets me when people don't want to take certain compounds because of fear of bloat. That makes no since to me. That is what AI's are for.
BLOODWORK!! Like Bigherm said, how do you know your Aromatase inhibitor (AI) is legit without blood work?!