Enanthate is slow acting and long lasting. It usually takes 4-5 Weeks to fully start the gains etc which is why 12 Weeks gives good results. Running longer if not prepared takes more recovery. So if you run your ai too soon you can suffer from low estro. Low estro will stop your gains/recovery, sore creaky joints, swuishy boner and low libido. Estro within reson...has benefits like joints and water levels in cell$. Too high of estro gives bloat, low libido, etc. Ai's are strong which is why that super teeny .25 Mg acts so fast. It is that strong. Life is balance. The better the balance the happier your body will be. So around week 3-5 if nips get itchy/sensitive or bloating then add the ai. If ai is acting too strong...with adex go every third day or aromasin drop to ed. Listening to your body is key. Click on community....forums. Couple hoyrs reading will generally answer a dozen questions. Tons of great info!