First you need to derive the transfer function for the circuit. Say H(s), multiply that by 1/s which the unit step function, then take the inverse Laplace transform of that. It will give you a step response in time domain. Pole - zero analysis is for frequency domain. So after getting the H(s) function you can use matlab with control toolbox and signal processing toolbox to plot the pole and zero location,s trajectory etc. These are very easily done using MatLab. Read their control toolbox manual for detail steps. The location as well as the locus(trajectory) of the pole and zero will indicate stability for your system or whether there is a doublet that can affect settling time in your circuit. Hope this helps.