The minimum eligibility criteria to study B.Com (//B.Com) is 12th and so you needn't wait until the completion of CA to study B.Com (//B.Com) . You can study right now. But one year B.Com (//B.Com) degrees are not that valid while looking for opportunities. Companies prefer Candidates who have completed regular and full studies. So it might be a dent there. But just to answer your question, you can study B.Com (//B.Com) even now.