Drinking alcohol while on cycle is negative for many reasons. So you just have to balance what matters to you. Progress and maximizing the cycle or having some drinks. If you keep it to a minumum you minimize any adverse affects. It's much like diet. You can stay on track and the more days or meals that you are not, the more that will adversely affect your results
I believe there are studies that show alcohol can inhibit muscle growth and development to a small degree. I hardly drink alcohol as it is (One or two cans/bottles per month tops) and plan to stop altogether once I start my first cycle tomorrow. I never cared for drinking in the first place.