It's ok for your EASY to be more like EASAEAS if there is a short nap. Also though LO might not make it a full 3.5hrs to the next feed if has only had a short nap. You need to count the next A time from when he woke form the nap, not when he 'should' have woken from the nap. So watch out for E and S clashing and bring E a little earlier if needed.