Working full-time with a part time job??

Hi everyone! I have a question and am hoping for some input.. I just passed my boards July 15th and am starting my first job September 8th, on a med-surg floor at nights (7p-8a). I was talking to my parents, who are both workaholics, and they seem to think that working 3 thirteen hour shifts a week will leave me with plenty of extra time to find another, part-time job. My question is this- while I obviously would wait a few months to settle into my first job before looking for another, is it realistic/ manageable to have another part-time job, or does 3 thirteen hour shifts leave you completely exhausted? I would just like advice because I myself am definitely not a workaholic but the extra $ would be helpful.. I know I can wait and see how everything plays out but I was just wondering how many RN's out there working 3 x/week have another job as well. Thank you so much in advance- any advice and suggestions are greatly appreciated..