Yeah, you only need a credit average and a bit of charisma to transfer over to a Comm/Arts. It's one of the easiest transfers in the university between those courses. I didn't have a problem with it but when transferring, you'll have to talk to the subdean and make sure you know what arts major you want to do and exactly why.
You can transfer at the end of any semester although it doesn't really matter if you don't do it straight away as you can still complete your commerce subjects in the meantime.