My understanding is that you must have a few years of work experience as a Case Manager in order to sit for the CCM or ACM exams. Thus, there is no way for you to get certified in these two prior to becoming a Case Manager. Please check the requirements here:
Commission for Case Management Certification (CCM): Certification & Renewal | CCMC
American Case Management Association: ACMA : American Case Management Association
Good news, with your ten years of clinical work experience, you may also have connections in the world of nursing that will help you to land your first CM job. Talk to a hiring manger of Case Management and ask that person the best way to be considered for an entry level position now or in the near future. A great place to start is your current employer or your former employers. Good luck!