You definitely need an AI from the first day of the cycle. It is a huge mistake many bodybuilders do, when they wait for the side effects to appear before they start using an AI. Use aromasin with these compounds. The best starting point is 10-12.5 mgs (depending on the tabs) EOD, and then you will see if you need more, or this is just fine. If you start feeling like you need more, first bump it to ED, and only then consider increasing the dosage to 20-25 mgs. Remember - you still need some estrogen in your body, so you do not need to kill it, just keep it balanced and under control.