Can someone help me on how can I get second order plus time delay model from the input-output data.

I have a set of input and output data of a process and I need to fit it into a second order plus time delay. I used the system identification app and imported the data and estimated using transfer function model. Here they asked about number of poles and zeros and input delay if any. But I have no idea about input or output delay. I just want to fit these data into SOPTD model.