Since the checkride is usually done (don't know of any cases not) in the left seat, you should probably be very comfortable over there. I had my commercial students do a few flights from the right seat to get a feel for it if they were doing well from the left seat. Talk to your CFI and when both of you are comfy with progress, then it probably wouldn't hurt to try a flight or three from the right seat. My thought is to keep the majority of the training to the left seat though. For one you are already used to it and that should help get the overall time for the commercial certificate down. Then once you have a solid foundation of the maneuvers and pass the commercial, you can focus on transitioning to the right seat which has proved to be harder for some than others. After you feel comfy in the right seat, simply bring all the skills from the commercial together and you are ready for your CFI checkride.