you can find[1] Q0 (and n of the CPE) by using your Z-fitting software[2]; also, you can get some hints reading the manual guide or even the help, in the menu.
1. Capacitance Value from CPE, RParallel: A Calculator http://www.consultrsr.net/resources/eis/cpecalc.htm ; see, also: http://www.consultrsr.net/resources/eis/zarc.htm#eqn3
2. https://www.researchgate.net/post/What_is_the_best_software_to_fit_EIS_data ; see, also: https://www.researchgate.net/post/Im_looking_for_zview_software_for_EIS_data_analysis_Can_anyone_help_me